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Lao J, Zhou T. Manipulating chiral Majorana mode with additional potential in superconductor-Chern insulator heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:405702. [PMID: 38955340 DOI: 10.1088/1361-648x/ad5e2c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2024] [Accepted: 07/02/2024] [Indexed: 07/04/2024]
Abstract
We employed the self-consistent Bogoliubov-de Gennes equations to explore the states of chiral Majorana mode in quantum anomalous Hall insulators in proximity to a superconductor, leading to the development of an extensive topological phase diagram. Our investigation focused on how an additional potential affects the separation of chiral Majorana modes across different phase conditions. We substantiated our findings by examining the zero-energy Local Density of States spectrum and the probability distribution of the chiral Majorana modes. We established the universality of chiral Majorana mode separation by applying an additional potential. This finding serves as a vital resource for future endeavors aimed at controlling and detecting these particles, thereby contributing to the advancement of quantum computing and condensed matter physics.
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Affiliation(s)
- Junming Lao
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou 510006, People's Republic of China
| | - Tao Zhou
- Guangdong Basic Research Center of Excellence for Structure and Fundamental Interactions of Matter, Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics, South China Normal University, Guangzhou 510006, People's Republic of China
- Guangdong-Hong Kong Joint Laboratory of Quantum Matter, Frontier Research Institute for Physics, South China Normal University, Guangzhou 510006, People's Republic of China
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2
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Guo Z, Han M, Zeng S, Yin Z, Tan J, Niu K, Zhao E, Zhao Y, Liu B, Zou X, Lin J. Intrinsic Grain Boundary Structure and Enhanced Defect States in Air-Sensitive Polycrystalline 1T'-WTe 2 Monolayer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2402219. [PMID: 38843883 DOI: 10.1002/adma.202402219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Revised: 05/03/2024] [Indexed: 06/15/2024]
Abstract
Monolayer WTe2 has attracted significant attention for its unconventional superconductivity and topological edge states. However, its air sensitivity poses challenges for studying intrinsic defect structures. This study addresses this issue using a custom-built inert gas interconnected system, and investigate the intrinsic grain boundary (GB) structures of monolayer polycrystalline 1T' WTe2 grown by nucleation-controlled chemical vapor deposition (CVD) method. These findings reveal that GBs in this system are predominantly governed by W-Te rhombi with saturated coordination, resulting in three specific GB prototypes without dislocation cores. The GBs exhibit anisotropic orientations influenced by kinks formed from these fundamental units, which in turn affect the distribution of grains in various shapes within polycrystalline flakes. Scanning tunneling microscopy/spectroscopy (STM/S) analysis further reveals metallic states along the intrinsic 120° twin grain boundary (TGB), consistent with computed band structures. This systematic exploration of GBs in air-sensitive 1T' WTe2 monolayers provides valuable insights into emerging GB-related phenomena.
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Affiliation(s)
- Zenglong Guo
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Mengjiao Han
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Shengfeng Zeng
- Shenzhen Geim Graphene Center, Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Zhouyi Yin
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Junyang Tan
- Shenzhen Geim Graphene Center, Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Kangdi Niu
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Erding Zhao
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Yue Zhao
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Bilu Liu
- Shenzhen Geim Graphene Center, Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Xiaolong Zou
- Shenzhen Geim Graphene Center, Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Junhao Lin
- Department of Physics and Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
- Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area (Guangdong), Shenzhen, 518045, China
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3
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Lu Z, Hou S, Lin R, Shi J, Wu Q, Lin L, Shi J, Yang Y, Lambert C, Hong W. Conductance Quantization in 2D Semi-Metallic Transition Metal Dichalcogenides. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2311491. [PMID: 38682729 DOI: 10.1002/smll.202311491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 03/09/2024] [Indexed: 05/01/2024]
Abstract
Conductance quantization of 2D materials is significant for understanding the charge transport at the atomic scale, which provides a platform to manipulate the quantum states, showing promising applications for nanoelectronics and memristors. However, the conventional methods for investigating conductance quantization are only applicable to materials consisting of one element, such as metal and graphene. The experimental observation of conductance quantization in transition metal dichalcogenides (TMDCs) with complex compositions and structures remains a challenge. To address this issue, an approach is proposed to characterize the charge transport across a single atom in TMDCs by integrating in situ synthesized 1T'-WTe2 electrodes with scanning tunneling microscope break junction (STM-BJ) technique. The quantized conductance of 1T'-WTe2 is measured for the first time, and the quantum states can be modulated by stretching speed and solvent. Combined with theoretical calculations, the evolution of quantized and corresponding configurations during the break junction process is demonstrated. This work provides a facile and reliable avenue to characterize and modulate conductance quantization of 2D materials, intensively expanding the research scope of quantum effects in diverse materials.
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Affiliation(s)
- Zhixing Lu
- Engineering Research Center of Polymer Green Recycling of Ministry of Education, College of Environmental and Resource Sciences, Fujian Normal University, Fuzhou, 350117, China
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Songjun Hou
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Rongjian Lin
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Jie Shi
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Qingqing Wu
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Luchun Lin
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Jia Shi
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Yang Yang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China
| | - Colin Lambert
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Wenjing Hong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China
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4
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Zhai W, Li Z, Wang Y, Zhai L, Yao Y, Li S, Wang L, Yang H, Chi B, Liang J, Shi Z, Ge Y, Lai Z, Yun Q, Zhang A, Wu Z, He Q, Chen B, Huang Z, Zhang H. Phase Engineering of Nanomaterials: Transition Metal Dichalcogenides. Chem Rev 2024; 124:4479-4539. [PMID: 38552165 DOI: 10.1021/acs.chemrev.3c00931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Crystal phase, a critical structural characteristic beyond the morphology, size, dimension, facet, etc., determines the physicochemical properties of nanomaterials. As a group of layered nanomaterials with polymorphs, transition metal dichalcogenides (TMDs) have attracted intensive research attention due to their phase-dependent properties. Therefore, great efforts have been devoted to the phase engineering of TMDs to synthesize TMDs with controlled phases, especially unconventional/metastable phases, for various applications in electronics, optoelectronics, catalysis, biomedicine, energy storage and conversion, and ferroelectrics. Considering the significant progress in the synthesis and applications of TMDs, we believe that a comprehensive review on the phase engineering of TMDs is critical to promote their fundamental studies and practical applications. This Review aims to provide a comprehensive introduction and discussion on the crystal structures, synthetic strategies, and phase-dependent properties and applications of TMDs. Finally, our perspectives on the challenges and opportunities in phase engineering of TMDs will also be discussed.
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Affiliation(s)
- Wei Zhai
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Zijian Li
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Yongji Wang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Li Zhai
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM), City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Yao Yao
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Siyuan Li
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Lixin Wang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Hua Yang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Banlan Chi
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Jinzhe Liang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Zhenyu Shi
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Yiyao Ge
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
| | - Zhuangchai Lai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Qinbai Yun
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - An Zhang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Zhiying Wu
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Qiyuan He
- Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong 999077, China
| | - Bo Chen
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- State Key Laboratory of Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), School of Chemistry and Life Sciences, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
| | - Zhiqi Huang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Hua Zhang
- Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM), City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Hong Kong Institute for Clean Energy, City University of Hong Kong, Kowloon, Hong Kong 999077, China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518057, China
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5
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Jamwal P, Ahuja R, Kumar R. Van Hove singularity driven enhancement of superconductivity in two-dimensional tungsten monofluoride (WF). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:245001. [PMID: 38411011 DOI: 10.1088/1361-648x/ad2d47] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 02/26/2024] [Indexed: 02/28/2024]
Abstract
Superconductivity in two-dimensional materials has gained significant attention in the last few years. In this work, we report phonon-mediated superconductivity investigations in monolayer Tungsten monofluoride (WF) by solving anisotropic Migdal Eliashberg equations as implemented in EPW. By employing first-principles calculations, our examination of phonon dispersion spectra suggests that WF is dynamically stable. Our results show that WF has weak electron-phonon coupling (EPC) strength (λ) of 0.49 with superconducting transition temperature (Tc) of 2.6 K. A saddle point is observed at 0.11 eV below the Fermi level (EF) of WF, which corresponds to the Van Hove singularity (VHS). On shifting the Fermi level to the VHS by hole doping (3.7 × 1014cm-2), the EPC strength increases to 0.93, which leads to an increase in theTcto 11 K. However, the superconducting transition temperature of both pristine and doped WF increases to approximately 7.2 K and 17.2 K, respectively, by applying the Full Bandwidth (FBW) anisotropic Migdal-Eliashberg equations. Our results provide a platform for the experimental realization of superconductivity in WF and enhancement of the superconducting transition temperature by adjusting the position ofEFto the VHS.
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Affiliation(s)
- Prarena Jamwal
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India
| | - Rajeev Ahuja
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India
- Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala 75120, Sweden
| | - Rakesh Kumar
- Department of Physics, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India
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6
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Gassner S, Weber CS, Claassen M. Light-induced switching between singlet and triplet superconducting states. Nat Commun 2024; 15:1776. [PMID: 38413590 PMCID: PMC10899631 DOI: 10.1038/s41467-024-45949-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 02/08/2024] [Indexed: 02/29/2024] Open
Abstract
While the search for topological triplet-pairing superconductivity has remained a challenge, recent developments in optically stabilizing metastable superconducting states suggest a new route to realizing this elusive phase. Here, we devise a testable theory of competing superconducting orders that permits ultrafast switching to an opposite-parity superconducting phase in centrosymmetric crystals with strong spin-orbit coupling. Using both microscopic and phenomenological models, we show that dynamical inversion symmetry breaking with a tailored light pulse can induce odd-parity (spin triplet) order parameter oscillations in a conventional even-parity (spin singlet) superconductor, which when driven strongly can send the system to a competing minimum in its free energy landscape. Our results provide new guiding principles for engineering unconventional electronic phases using light, suggesting a fundamentally non-equilibrium route toward realizing topological superconductivity.
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Affiliation(s)
- Steven Gassner
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Clara S Weber
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Institut für Theorie der Statistischen Physik, RWTH Aachen and JARA - Fundamentals of Future Information Technology, D-52056, Aachen, Germany
| | - Martin Claassen
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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7
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Liu A, Zhang X, Liu Z, Li Y, Peng X, Li X, Qin Y, Hu C, Qiu Y, Jiang H, Wang Y, Li Y, Tang J, Liu J, Guo H, Deng T, Peng S, Tian H, Ren TL. The Roadmap of 2D Materials and Devices Toward Chips. NANO-MICRO LETTERS 2024; 16:119. [PMID: 38363512 PMCID: PMC10873265 DOI: 10.1007/s40820-023-01273-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/30/2023] [Indexed: 02/17/2024]
Abstract
Due to the constraints imposed by physical effects and performance degradation, silicon-based chip technology is facing certain limitations in sustaining the advancement of Moore's law. Two-dimensional (2D) materials have emerged as highly promising candidates for the post-Moore era, offering significant potential in domains such as integrated circuits and next-generation computing. Here, in this review, the progress of 2D semiconductors in process engineering and various electronic applications are summarized. A careful introduction of material synthesis, transistor engineering focused on device configuration, dielectric engineering, contact engineering, and material integration are given first. Then 2D transistors for certain electronic applications including digital and analog circuits, heterogeneous integration chips, and sensing circuits are discussed. Moreover, several promising applications (artificial intelligence chips and quantum chips) based on specific mechanism devices are introduced. Finally, the challenges for 2D materials encountered in achieving circuit-level or system-level applications are analyzed, and potential development pathways or roadmaps are further speculated and outlooked.
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Affiliation(s)
- Anhan Liu
- School of Integrated Circuits and Beijing National Research Center for Information Science and Technology (BNRist), Tsinghua University, Beijing, 100049, People's Republic of China
| | - Xiaowei Zhang
- School of Integrated Circuits and Beijing National Research Center for Information Science and Technology (BNRist), Tsinghua University, Beijing, 100049, People's Republic of China
| | - Ziyu Liu
- School of Microelectronics, Fudan University, Shanghai, 200433, People's Republic of China
| | - Yuning Li
- School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing, 100044, People's Republic of China
| | - Xueyang Peng
- High-Frequency High-Voltage Device and Integrated Circuits R&D Center, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, People's Republic of China
- School of Integrated Circuits, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Xin Li
- State Key Laboratory of Dynamic Measurement Technology, Shanxi Province Key Laboratory of Quantum Sensing and Precision Measurement, North University of China, Taiyuan, 030051, People's Republic of China
| | - Yue Qin
- State Key Laboratory of Dynamic Measurement Technology, Shanxi Province Key Laboratory of Quantum Sensing and Precision Measurement, North University of China, Taiyuan, 030051, People's Republic of China
| | - Chen Hu
- High-Frequency High-Voltage Device and Integrated Circuits R&D Center, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, People's Republic of China
- School of Integrated Circuits, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Yanqing Qiu
- High-Frequency High-Voltage Device and Integrated Circuits R&D Center, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, People's Republic of China
- School of Integrated Circuits, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Han Jiang
- School of Microelectronics, Fudan University, Shanghai, 200433, People's Republic of China
| | - Yang Wang
- School of Microelectronics, Fudan University, Shanghai, 200433, People's Republic of China
| | - Yifan Li
- School of Integrated Circuits and Beijing National Research Center for Information Science and Technology (BNRist), Tsinghua University, Beijing, 100049, People's Republic of China
| | - Jun Tang
- State Key Laboratory of Dynamic Measurement Technology, Shanxi Province Key Laboratory of Quantum Sensing and Precision Measurement, North University of China, Taiyuan, 030051, People's Republic of China
| | - Jun Liu
- State Key Laboratory of Dynamic Measurement Technology, Shanxi Province Key Laboratory of Quantum Sensing and Precision Measurement, North University of China, Taiyuan, 030051, People's Republic of China
| | - Hao Guo
- State Key Laboratory of Dynamic Measurement Technology, Shanxi Province Key Laboratory of Quantum Sensing and Precision Measurement, North University of China, Taiyuan, 030051, People's Republic of China.
| | - Tao Deng
- School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing, 100044, People's Republic of China.
| | - Songang Peng
- High-Frequency High-Voltage Device and Integrated Circuits R&D Center, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, People's Republic of China.
- IMECAS-HKUST-Joint Laboratory of Microelectronics, Beijing, 100029, People's Republic of China.
| | - He Tian
- School of Integrated Circuits and Beijing National Research Center for Information Science and Technology (BNRist), Tsinghua University, Beijing, 100049, People's Republic of China.
| | - Tian-Ling Ren
- School of Integrated Circuits and Beijing National Research Center for Information Science and Technology (BNRist), Tsinghua University, Beijing, 100049, People's Republic of China.
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Que Y, Chan YH, Jia J, Das A, Tong Z, Chang YT, Cui Z, Kumar A, Singh G, Mukherjee S, Lin H, Weber B. A Gate-Tunable Ambipolar Quantum Phase Transition in a Topological Excitonic Insulator. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2309356. [PMID: 38010877 DOI: 10.1002/adma.202309356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/26/2023] [Indexed: 11/29/2023]
Abstract
Coulomb interactions among electrons and holes in 2D semimetals with overlapping valence and conduction bands can give rise to a correlated insulating ground state via exciton formation and condensation. One candidate material in which such excitonic state uniquely combines with non-trivial band topology are atomic monolayers of tungsten ditelluride (WTe2 ), in which a 2D topological excitonic insulator (2D TEI) forms. However, the detailed mechanism of the 2D bulk gap formation in WTe2 , in particular with regard to the role of Coulomb interactions, has remained a subject of ongoing debate. Here, it shows that WTe2 is susceptible to a gate-tunable quantum phase transition, evident from an abrupt collapse of its 2D bulk energy gap upon ambipolar field-effect doping. Such gate tunability of a 2D TEI, into either n- and p-type semimetals, promises novel handles of control over non-trivial 2D superconductivity with excitonic pairing.
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Affiliation(s)
- Yande Que
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Yang-Hao Chan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106319, Taiwan
- Physics Division, National Center of Theoretical Physics, Taipei, 10617, Taiwan
| | - Junxiang Jia
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Anirban Das
- Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
- Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
| | - Zhengjue Tong
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Yu-Tzu Chang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106319, Taiwan
| | - Zhenhao Cui
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Amit Kumar
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Gagandeep Singh
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Shantanu Mukherjee
- Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
- Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
- Quantum Centre for Diamond and Emergent Materials, Indian Institute of Technology Madras, Chennai, Tamil Nadu, 600036, India
| | - Hsin Lin
- Institute of Physics, Academia Sinica, Taipei, 115201, Taiwan
| | - Bent Weber
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
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9
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Wu S, Dai M, Li H, Li R, Han Z, Hu W, Zhao Z, Hou Y, Gou H, Zou R, Chen Y, Luo X, Zhao X. Atomically Unraveling Highly Crystalline Self-Intercalated Tantalum Sulfide with Correlated Stacking Registry-Dependent Magnetism. NANO LETTERS 2024; 24:378-385. [PMID: 38117785 DOI: 10.1021/acs.nanolett.3c04122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
In self-intercalated two-dimensional (ic-2D) materials, understanding the local chemical environment and the topology of the filling site remains elusive, and the subsequent correlation with the macroscopically manifested physical properties has rarely been investigated. Herein, highly crystalline gram-scale ic-2D Ta1.33S2 crystals were successfully grown by the high-pressure high-temperature method. Employing combined atomic-resolution scanning transmission electron microscopy annular dark field imaging and density functional theory calculations, we systematically unveiled the atomic structures of an atlas of stacking registries in a well-defined √3(a) × √3(a) Ta1.33S2 superlattice. Ferromagnetic order was observed in the AC' stacking registry, and it evolves into an antiferromagnetic state in AA/AB/AB' stacking registries; the AA' stacking registry shows ferrimagnetic ordering. Therefore, we present a novel approach for fabricating large-scale highly crystalline ic-2D crystals and shed light on a powerful means of modulating the magnetic order of ic-2D systems via stacking engineering, i.e., stackingtronics.
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Affiliation(s)
- Shengqiang Wu
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Minzhi Dai
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
| | - Hang Li
- Center for High Pressure Science and Technology Advanced Research, Beijing 100193, China
| | - Runlai Li
- College of Polymer Science & Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China
| | - Ziyi Han
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
| | - Wenchao Hu
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Zijing Zhao
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Yanglong Hou
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Huiyang Gou
- Center for High Pressure Science and Technology Advanced Research, Beijing 100193, China
| | - Ruqiang Zou
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Yongjin Chen
- Center for High Pressure Science and Technology Advanced Research, Beijing 100193, China
| | - Xin Luo
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
| | - Xiaoxu Zhao
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
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10
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Wang Z, Liu Y, Ji C, Wang J. Quantum phase transitions in two-dimensional superconductors: a review on recent experimental progress. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2023; 87:014502. [PMID: 38086096 DOI: 10.1088/1361-6633/ad14f3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 12/12/2023] [Indexed: 12/30/2023]
Abstract
Superconductor-insulator/metal transition (SMT) as a paradigm of quantum phase transition has been a research highlight over the last three decades. Benefit from recent developments in the fabrication and measurements of two-dimensional (2D) superconducting films and nanodevices, unprecedented quantum phenomena have been revealed in the quantum phase transitions of 2D superconductors. In this review, we introduce the recent progress on quantum phase transitions in 2D superconductors, focusing on the quantum Griffiths singularity (QGS) and anomalous metal state. Characterized by a divergent critical exponent when approaching zero temperature, QGS of SMT is discovered in ultrathin crystalline Ga films and subsequently detected in various 2D superconductors. The universality of QGS indicates the profound influence of quenched disorder on quantum phase transitions. Besides, in a 2D superconducting system, whether a metallic ground state can exist is a long-sought mystery. Early experimental studies indicate an intermediate metallic state in the quantum phase transition of 2D superconductors. Recently, in high-temperature superconducting films with patterned nanopores, a robust anomalous metal state (i.e. quantum metal or Bose metal) has been detected, featured as the saturated resistance in the low temperature regime. Moreover, the charge-2equantum oscillations are observed in nanopatterned films, indicating the bosonic nature of the anomalous metal state and ending the debate on whether bosons can exist as a metal. The evidences of the anomalous metal states have also been reported in crystalline epitaxial thin films and exfoliated nanoflakes, as well as granular composite films. High quality filters are used in these works to exclude the influence of external high frequency noises in ultralow temperature measurements. The observations of QGS and metallic ground states in 2D superconductors not only reveal the prominent role of quantum fluctuations and dissipations but also provide new perspective to explore quantum phase transitions in superconducting systems.
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Affiliation(s)
- Ziqiao Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Yi Liu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, People's Republic of China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing 100872, People's Republic of China
| | - Chengcheng Ji
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Hefei National Laboratory, Hefei 230088, People's Republic of China
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China
- Hefei National Laboratory, Hefei 230088, People's Republic of China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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11
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Onyszczak M, Uzan-Narovlansky AJ, Tang Y, Wang P, Jia Y, Yu G, Song T, Singha R, Khoury JF, Schoop LM, Wu S. A platform for far-infrared spectroscopy of quantum materials at millikelvin temperatures. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:103903. [PMID: 37823766 DOI: 10.1063/5.0160321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 09/25/2023] [Indexed: 10/13/2023]
Abstract
Optical spectroscopy of quantum materials at ultralow temperatures is rarely explored, yet it may provide critical characterizations of quantum phases not possible using other approaches. We describe the development of a novel experimental platform that enables optical spectroscopic studies, together with standard electronic transport, of materials at millikelvin temperatures inside a dilution refrigerator. The instrument is capable of measuring both bulk crystals and micrometer-sized two-dimensional van der Waals materials and devices. We demonstrate its performance by implementing photocurrent-based Fourier transform infrared spectroscopy on a monolayer WTe2 device and a multilayer 1T-TaS2 crystal, with a spectral range available from the near-infrared to the terahertz regime and in magnetic fields up to 5 T. In the far-infrared regime, we achieve spectroscopic measurements at a base temperature as low as ∼43 mK and a sample electron temperature of ∼450 mK. Possible experiments and potential future upgrades of this versatile instrumental platform are envisioned.
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Affiliation(s)
- Michael Onyszczak
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | | | - Yue Tang
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Pengjie Wang
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Yanyu Jia
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Guo Yu
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
- Department of Electrical and Computer Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Tiancheng Song
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Ratnadwip Singha
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Jason F Khoury
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Leslie M Schoop
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Sanfeng Wu
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
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12
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Rizzo DJ, Zhang J, Jessen BS, Ruta FL, Cothrine M, Yan J, Mandrus DG, Nagler SE, Taniguchi T, Watanabe K, Fogler MM, Pasupathy AN, Millis AJ, Rubio A, Hone JC, Dean CR, Basov DN. Polaritonic Probe of an Emergent 2D Dipole Interface. NANO LETTERS 2023; 23:8426-8435. [PMID: 37494638 DOI: 10.1021/acs.nanolett.3c01611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
The use of work-function-mediated charge transfer has recently emerged as a reliable route toward nanoscale electrostatic control of individual atomic layers. Using α-RuCl3 as a 2D electron acceptor, we are able to induce emergent nano-optical behavior in hexagonal boron nitride (hBN) that arises due to interlayer charge polarization. Using scattering-type scanning near-field optical microscopy (s-SNOM), we find that a thin layer of α-RuCl3 adjacent to an hBN slab reduces the propagation length of hBN phonon polaritons (PhPs) in significant excess of what can be attributed to intrinsic optical losses. Concomitant nano-optical spectroscopy experiments reveal a novel resonance that aligns energetically with the region of excess PhP losses. These experimental observations are elucidated by first-principles density-functional theory and near-field model calculations, which show that the formation of a large interfacial dipole suppresses out-of-plane PhP propagation. Our results demonstrate the potential utility of charge-transfer heterostructures for tailoring optoelectronic properties of 2D insulators.
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Affiliation(s)
- Daniel J Rizzo
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Jin Zhang
- Theory Department, Max Planck Institute for Structure and Dynamics of Matter and Center for Free-Electron Laser Science, 22761 Hamburg, Germany
| | - Bjarke S Jessen
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Francesco L Ruta
- Department of Physics, Columbia University, New York, New York 10027, United States
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
| | - Matthew Cothrine
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jiaqiang Yan
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - David G Mandrus
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Stephen E Nagler
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Michael M Fogler
- Department of Physics, University of California San Diego, La Jolla, California 92093, United States
| | - Abhay N Pasupathy
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Andrew J Millis
- Department of Physics, Columbia University, New York, New York 10027, United States
- Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, United States
| | - Angel Rubio
- Theory Department, Max Planck Institute for Structure and Dynamics of Matter and Center for Free-Electron Laser Science, 22761 Hamburg, Germany
- Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, United States
- Nano-Bio Spectroscopy Group, Universidad del País Vasco UPV/EHU, San Sebastián 20018, Spain
| | - James C Hone
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Cory R Dean
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - D N Basov
- Department of Physics, Columbia University, New York, New York 10027, United States
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13
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Cui X, Yan H, Yan X, Zhou K, Cai Y. Promoted Electronic Coupling of Acoustic Phonon Modes in Doped Semimetallic MoTe 2. ACS NANO 2023; 17:16530-16538. [PMID: 37646299 DOI: 10.1021/acsnano.3c01229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
As a prototype of the Weyl superconductor, layered molybdenum ditelluride (MoTe2) encompasses two semimetallic phases (1T' and Td) which differentiate from each other via a slight tilting of the out-of-plane lattice. Both phases are subjected to serious phase mixing, which complicates the analysis of its origin of superconductivity. Herein, we explore the electron-phonon coupling (EPC) of the monolayer semimetallic MoTe2, without phase ambiguity under this thickness limit. Apart from the hardening or softening of the phonon modes, the strength of the EPC can be strongly modulated by doping. Specifically, longitudinal and out-of-plane acoustic modes are significantly activated for electron doped MoTe2. This is ascribed to the presence of rich valley states and equispaced nesting bands, which are dynamically populated under charge doping. Through comparing the monolayer and bilayer MoTe2, the strength of EPC is found to be less likely to depend on thickness for neutral samples but clearly promoted for thinner samples with electron doping, while for hole doping, the strength alters more significantly with the thickness than doping. Our work explains the issue of the doping sensitivity of the superconductivity in semimetallic MoTe2 and establishes the critical role of activating acoustic phonons in such low-dimensional materials.
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Affiliation(s)
- Xiangyue Cui
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau, 999078, China
| | - Hejin Yan
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau, 999078, China
| | - Xuefei Yan
- School of Microelectronics Science and Technology, Sun Yat-Sen University, Zhuhai 519082, China
- Guangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems, Sun Yat-Sen University, Zhuhai 519082, China
| | - Kun Zhou
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore
- Environmental Process Modelling Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, 637141 Singapore
| | - Yongqing Cai
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau, 999078, China
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14
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Lu X, Zhang S, Wang Y, Gao X, Yang K, Guo Z, Gao Y, Ye Y, Han Z, Liu J. Synergistic correlated states and nontrivial topology in coupled graphene-insulator heterostructures. Nat Commun 2023; 14:5550. [PMID: 37689704 PMCID: PMC10492827 DOI: 10.1038/s41467-023-41293-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 08/29/2023] [Indexed: 09/11/2023] Open
Abstract
Graphene has aroused great attention due to the intriguing properties associated with its low-energy Dirac Hamiltonian. When graphene is coupled with a correlated insulating substrate, electronic states that cannot be revealed in either individual layer may emerge in a synergistic manner. Here, we theoretically study the correlated and topological states in Coulomb-coupled and gate-tunable graphene-insulator heterostructures. By electrostatically aligning the electronic bands, charge carriers transferred between graphene and the insulator can yield a long-wavelength electronic crystal at the interface, exerting a superlattice Coulomb potential on graphene and generating topologically nontrivial subbands. This coupling can further boost electron-electron interaction effects in graphene, leading to a spontaneous bandgap formation at the Dirac point and interaction-enhanced Fermi velocity. Reciprocally, the electronic crystal at the interface is substantially stabilized with the help of cooperative interlayer Coulomb coupling. We propose a number of substrate candidates for graphene to experimentally demonstrate these effects.
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Affiliation(s)
- Xin Lu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Shihao Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yaning Wang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China
| | - Xiang Gao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, 030006, Taiyuan, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, 030006, Taiyuan, China
| | - Kaining Yang
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, 030006, Taiyuan, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, 030006, Taiyuan, China
| | - Zhongqing Guo
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yuchen Gao
- Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China
- State Key Lab for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing, 100871, China
| | - Yu Ye
- Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China
- State Key Lab for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing, 100871, China
| | - Zheng Han
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, 030006, Taiyuan, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, 030006, Taiyuan, China
| | - Jianpeng Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai, 201210, China.
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15
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Randle MD, Hosoda M, Deacon RS, Ohtomo M, Zellekens P, Watanabe K, Taniguchi T, Okazaki S, Sasagawa T, Kawaguchi K, Sato S, Ishibashi K. Gate-Defined Josephson Weak-Links in Monolayer WTe 2. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2301683. [PMID: 37358032 DOI: 10.1002/adma.202301683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 06/15/2023] [Indexed: 06/27/2023]
Abstract
Systems combining superconductors with topological insulators offer a platform for the study of Majorana bound states and a possible route to realize fault tolerant topological quantum computation. Among the systems being considered in this field, monolayers of tungsten ditelluride (WTe2 ) have a rare combination of properties. Notably, it has been demonstrated to be a quantum spin Hall insulator (QSHI) and can easily be gated into a superconducting state. Measurements on gate-defined Josephson weak-link devices fabricated using monolayer WTe2 are reported. It is found that consideration of the 2D superconducting leads are critical in the interpretation of magnetic interference in the resulting junctions. The reported fabrication procedures suggest a facile way to produce further devices from this technically challenging material and the results mark the first step toward realizing versatile all-in-one topological Josephson weak-links using monolayer WTe2 .
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Affiliation(s)
- Michael D Randle
- Advanced Device Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Masayuki Hosoda
- Fujitsu Research, Fujitsu Ltd., 10-1 Morinosato-Wakamiya, Atsugi, Kanagawa, 243-0197, Japan
| | - Russell S Deacon
- Advanced Device Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Manabu Ohtomo
- Fujitsu Research, Fujitsu Ltd., 10-1 Morinosato-Wakamiya, Atsugi, Kanagawa, 243-0197, Japan
| | - Patrick Zellekens
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Shota Okazaki
- Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
| | - Takao Sasagawa
- Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan
| | - Kenichi Kawaguchi
- Fujitsu Research, Fujitsu Ltd., 10-1 Morinosato-Wakamiya, Atsugi, Kanagawa, 243-0197, Japan
| | - Shintaro Sato
- Fujitsu Research, Fujitsu Ltd., 10-1 Morinosato-Wakamiya, Atsugi, Kanagawa, 243-0197, Japan
| | - Koji Ishibashi
- Advanced Device Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
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16
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Tang F, Wang P, Wang Q, Gan Y, Lyu J, Mi X, He M, Zhang L, Smet JH. Ambipolar Superconductivity with Strong Pairing Interaction in Monolayer 1T'-MoTe 2. NANO LETTERS 2023; 23:7516-7523. [PMID: 37540083 PMCID: PMC10450800 DOI: 10.1021/acs.nanolett.3c02033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/14/2023] [Indexed: 08/05/2023]
Abstract
Gate tunable two-dimensional (2D) superconductors offer significant advantages in studying superconducting phase transitions. Here, we address superconductivity in exfoliated 1T'-MoTe2 monolayers with an intrinsic band gap of ∼7.3 meV using field effect doping. Despite large differences in the dispersion of the conduction and valence bands, superconductivity can be achieved easily for both electrons and holes. The onset of superconductivity occurs near 7-8 K for both charge carrier types. This temperature is much higher than that in bulk samples. Also the in-plane upper critical field is strongly enhanced and exceeds the BCS Pauli limit in both cases. Gap information is extracted using point-contact spectroscopy. The gap ratio exceeds multiple times the value expected for BCS weak-coupling. All of these observations suggest a strong enhancement of the pairing interaction.
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Affiliation(s)
- Fangdong Tang
- Max
Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Peipei Wang
- Department
of Physics and Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Qixing Wang
- Max
Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Yuan Gan
- Department
of Physics and Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jian Lyu
- Department
of Physics and Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xinrun Mi
- Low
Temperature Physics Laboratory, College of Physics & Center of
Quantum Materials and Devices, Chongqing
University, Chongqing 401331, China
| | - Mingquan He
- Low
Temperature Physics Laboratory, College of Physics & Center of
Quantum Materials and Devices, Chongqing
University, Chongqing 401331, China
| | - Liyuan Zhang
- Department
of Physics and Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jurgen H. Smet
- Max
Planck Institute for Solid State Research, Stuttgart 70569, Germany
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17
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Huang X, Jia L, Song X, Chen Y, Song Y, Yang K, Guo JG, Huang Y, Liu L, Wang Y. Observation of Two-Dimensional Type-II Superconductivity in Bulk 3R-TaSe 2 by Scanning Tunneling Spectroscopy. J Phys Chem Lett 2023; 14:7235-7240. [PMID: 37552580 DOI: 10.1021/acs.jpclett.3c01730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Here we report a low-temperature and vector-magnetic-field scanning tunneling microscopy/spectroscopy (STM/S) study on 3R-TaSe2. The sample surface was obtained by exfoliating a bulk 3R-TaSe2 single crystal in an ultrahigh-vacuum (UHV) chamber and then transferred in situ to STM. It was observed that the topmost layer shows a 3 × 3 charge density wave pattern at T = 4.2 K with metallic character in STS. The electronic characterization study by variable-temperature and magnetic field STS revealed that 3R-TaSe2 behaves as a type-II superconductor. More intriguingly, such superconductivity (SC) can survive under strong in-plane magnetic fields even up to 2.5 T and out-of-plane magnetic fields up to 0.7 T, exhibiting an anisotropic superconducting property. Temperature-dependent STS showed that 3R-TaSe2 undergoes a transition above 0.58 K. Our results may be important for understanding the intriguing SC properties of the 3R-phase van der Waals materials.
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Affiliation(s)
- Xinyu Huang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Liangguang Jia
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Xuan Song
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Yaoyao Chen
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Yanpeng Song
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Kai Yang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jian-Gang Guo
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yuan Huang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Liwei Liu
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
| | - Yeliang Wang
- School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China
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18
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Yuan F, Jia Y, Cheng G, Singha R, Lei S, Yao N, Wu S, Schoop LM. Atomic Resolution Imaging of Highly Air-Sensitive Monolayer and Twisted-Bilayer WTe 2. NANO LETTERS 2023; 23:6868-6874. [PMID: 37477415 DOI: 10.1021/acs.nanolett.3c01175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/22/2023]
Abstract
Bulk Td-WTe2 is a semimetal, while its monolayer counterpart is a two-dimensional (2D) topological insulator. Recently, electronic transport resembling a Luttinger liquid state was found in twisted-bilayer WTe2 (tWTe2) with a twist angle of ∼5°. Despite the strong interest in 2D WTe2 systems, little experimental information is available about their intrinsic microstructure, leaving obstacles in modeling their physical properties. The monolayer, and consequently tWTe2, are highly air-sensitive, and therefore, probing their atomic structures is difficult. In this study, we develop a robust method for atomic-resolution visualization of monolayers and tWTe2 obtained through mechanical exfoliation and fabrication. We confirm the high crystalline quality of mechanically exfoliated WTe2 samples and observe that tWTe2 with twist angles of ∼5 and ∼2° retains its pristine moiré structure without substantial deformations or reconstructions. The results provide a structural foundation for future electronic modeling of monolayer and tWTe2 moiré lattices.
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Affiliation(s)
- Fang Yuan
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Yanyu Jia
- Department of Physics, Princeton University, Princeton, New Jersey 08544, United States
| | - Guangming Cheng
- Princeton Materials Institute, Princeton University, Princeton, New Jersey 08544, United States
| | - Ratnadwip Singha
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Shiming Lei
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Nan Yao
- Princeton Materials Institute, Princeton University, Princeton, New Jersey 08544, United States
| | - Sanfeng Wu
- Department of Physics, Princeton University, Princeton, New Jersey 08544, United States
| | - Leslie M Schoop
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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19
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Zhang Y, Fei F, Liu R, Zhu T, Chen B, Qiu T, Zuo Z, Guo J, Tang W, Zhou L, Xi X, Wu X, Wu D, Zhong Z, Song F, Zhang R, Wang X. Enhanced Superconductivity and Upper Critical Field in Ta-Doped Weyl Semimetal T d -MoTe 2. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2207841. [PMID: 36905678 DOI: 10.1002/adma.202207841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 02/14/2023] [Indexed: 05/12/2023]
Abstract
2D transition metal dichalcogenides are promising platforms for next-generation electronics and spintronics. The layered Weyl semimetal (W,Mo)Te2 series features structural phase transition, nonsaturated magnetoresistance, superconductivity, and exotic topological physics. However, the superconducting critical temperature of the bulk (W,Mo)Te2 remains ultralow without applying a high pressure. Here, the significantly enhanced superconductivity is observed with a transition temperature as large as about 7.5 K in bulk Mo1- x Tax Te2 single crystals upon Ta doping (0 ≤ x ≤ 0.22), which is attributed to an enrichment of density of states at the Fermi level. In addition, an enhanced perpendicular upper critical field of 14.5 T exceeding the Pauli limit is also observed in Td -phase Mo1- x Tax Te2 (x = 0.08), indicating the possible emergence of unconventional mixed singlet-triplet superconductivity owing to the inversion symmetry breaking. This work provides a new pathway for exploring the exotic superconductivity and topological physics in transition metal dichalcogenides.
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Affiliation(s)
- Yong Zhang
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Fucong Fei
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Ruxin Liu
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Tongshuai Zhu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Bo Chen
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Tianyu Qiu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Zewen Zuo
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Jingwen Guo
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Wenchao Tang
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Lifan Zhou
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Xiaoxiang Xi
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Xiaoshan Wu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Di Wu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Zhicheng Zhong
- Key Laboratory of Magnetic Materials and Devices, Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences, Ningbo, 315201, China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China
| | - Rong Zhang
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
- Department of Physics, Xiamen University, Xiamen, 316005, China
| | - Xuefeng Wang
- Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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20
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Jarjour A, Ferguson GM, Schaefer BT, Lee M, Loh YL, Trivedi N, Nowack KC. Superfluid response of an atomically thin gate-tuned van der Waals superconductor. Nat Commun 2023; 14:2055. [PMID: 37045826 PMCID: PMC10097715 DOI: 10.1038/s41467-023-37210-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 03/03/2023] [Indexed: 04/14/2023] Open
Abstract
A growing number of two-dimensional superconductors are being discovered in the family of exfoliated van der Waals materials. Due to small sample volume, the superfluid response of these materials has not been characterized. Here, we use a local magnetic probe to directly measure this key property of the tunable, gate-induced superconducting state in MoS2. We find that the backgate changes the transition temperature non-monotonically whereas the superfluid stiffness at low temperature and the normal state conductivity monotonically increase. In some devices, we find direct signatures in agreement with a Berezinskii-Kosterlitz-Thouless transition, whereas in others we find a broadened onset of the superfluid response. We show that the observed behavior is consistent with disorder playing an important role in determining the properties of superconducting MoS2. Our work demonstrates that magnetic property measurements are within reach for superconducting devices based on exfoliated sheets and reveals that the superfluid response significantly deviates from simple BCS-like behavior.
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Affiliation(s)
- Alexander Jarjour
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA
| | - G M Ferguson
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA
| | - Brian T Schaefer
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA
| | - Menyoung Lee
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA
- School of Electrical and Computer Engineering, Cornell University, Ithaca, NY, USA
| | - Yen Lee Loh
- Department of Physics and Astrophysics, University of North Dakota, Grand Forks, ND, USA
| | - Nandini Trivedi
- Department of Physics, The Ohio State University, Columbus, OH, USA
| | - Katja C Nowack
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, USA.
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
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21
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Heider T, Bihlmayer G, Schusser J, Reinert F, Minár J, Blügel S, Schneider CM, Plucinski L. Geometry-Induced Spin Filtering in Photoemission Maps from WTe_{2} Surface States. PHYSICAL REVIEW LETTERS 2023; 130:146401. [PMID: 37084452 DOI: 10.1103/physrevlett.130.146401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/22/2022] [Accepted: 02/24/2023] [Indexed: 05/03/2023]
Abstract
We demonstrate that an important quantum material WTe_{2} exhibits a new type of geometry-induced spin filtering effect in photoemission, stemming from low symmetry that is responsible for its exotic transport properties. Through the laser-driven spin-polarized angle-resolved photoemission Fermi surface mapping, we showcase highly asymmetric spin textures of electrons photoemitted from the surface states of WTe_{2}. Such asymmetries are not present in the initial state spin textures, which are bound by the time-reversal and crystal lattice mirror plane symmetries. The findings are reproduced qualitatively by theoretical modeling within the one-step model photoemission formalism. The effect could be understood within the free-electron final state model as an interference due to emission from different atomic sites. The observed effect is a manifestation of time-reversal symmetry breaking of the initial state in the photoemission process, and as such it cannot be eliminated, but only its magnitude influenced, by special experimental geometries.
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Affiliation(s)
- Tristan Heider
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Gustav Bihlmayer
- Peter Grünberg Institut (PGI-1) and Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich and JARA, 52428 Jülich, Germany
| | - Jakub Schusser
- New Technologies-Research Center, University of West Bohemia, 30614 Pilsen, Czech Republic
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97070 Würzburg, Germany
| | - Friedrich Reinert
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97070 Würzburg, Germany
| | - Jan Minár
- New Technologies-Research Center, University of West Bohemia, 30614 Pilsen, Czech Republic
| | - Stefan Blügel
- Peter Grünberg Institut (PGI-1) and Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich and JARA, 52428 Jülich, Germany
| | - Claus M Schneider
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- Fakultät für Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany
- Physics Department, University of California, Davis, California 95616, USA
| | - Lukasz Plucinski
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
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22
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Song X, Singha R, Cheng G, Yeh YW, Kamm F, Khoury JF, Hoff BL, Stiles JW, Pielnhofer F, Batson PE, Yao N, Schoop LM. Synthesis of an aqueous, air-stable, superconducting 1T'-WS 2 monolayer ink. SCIENCE ADVANCES 2023; 9:eadd6167. [PMID: 36947621 PMCID: PMC10032609 DOI: 10.1126/sciadv.add6167] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 02/22/2023] [Indexed: 06/18/2023]
Abstract
Liquid-phase chemical exfoliation can achieve industry-scale production of two-dimensional (2D) materials for a wide range of applications. However, many 2D materials with potential applications in quantum technologies often fail to leave the laboratory setting because of their air sensitivity and depreciation of physical performance after chemical processing. We report a simple chemical exfoliation method to create a stable, aqueous, surfactant-free, superconducting ink containing phase-pure 1T'-WS2 monolayers that are isostructural to the air-sensitive topological insulator 1T'-WTe2. The printed film is metallic at room temperature and superconducting below 7.3 kelvin, shows strong anisotropic unconventional superconducting behavior with an in-plane and out-of-plane upper critical magnetic field of 30.1 and 5.3 tesla, and is stable at ambient conditions for at least 30 days. Our results show that chemical processing can make nontrivial 2D materials that were formerly only studied in laboratories commercially accessible.
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Affiliation(s)
- Xiaoyu Song
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Ratnadwip Singha
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Guangming Cheng
- Princeton Institute for Science and Technology of Materials, Princeton, NJ 08544, USA
| | - Yao-Wen Yeh
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
| | - Franziska Kamm
- Institute of Inorganic Chemistry, University of Regensburg, D-93040 Regensburg, Germany
| | - Jason F. Khoury
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Brianna L. Hoff
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Joseph W. Stiles
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Florian Pielnhofer
- Institute of Inorganic Chemistry, University of Regensburg, D-93040 Regensburg, Germany
| | - Philip E. Batson
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
| | - Nan Yao
- Princeton Institute for Science and Technology of Materials, Princeton, NJ 08544, USA
| | - Leslie M. Schoop
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
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23
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Verma S, Yadav R, Pandey A, Kaur M, Husale S. Investigating active area dependent high performing photoresponse through thin films of Weyl Semimetal WTe 2. Sci Rep 2023; 13:197. [PMID: 36604468 PMCID: PMC9814664 DOI: 10.1038/s41598-022-27200-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 12/28/2022] [Indexed: 01/06/2023] Open
Abstract
WTe2 is one of the wonder layered materials, displays interesting overlapping of electron-hole pairs, opening of the surface bandgap, anisotropy in its crystal structure and very much sought appealing material for room temperature broadband photodection applications. Here we report the photoresponse of WTe2 thin films and microchannel devices fabricated on silicon nitride substrates. A clear sharp rise in photocurrent observed under the illumination of visible (532 nm) and NIR wavelengths (1064 nm). The observed phoresponse is very convincing and repetitive for ON /OFF cycles of laser light illumination. The channel length dependence of photocurrent is noticed for few hundred nanometers to micrometers. The photocurrent, rise & decay times, responsivity and detectivity are studied using different channel lengths. Strikingly microchannel gives few orders of greater responsivity compared to larger active area investigated here. The responsivity and detectivity are observed as large as 29 A/W and 3.6 × 108 Jones respectively. The high performing photodetection properties indicate that WTe2 can be used as a broad band material for future optoelectronic applications.
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Affiliation(s)
- Sahil Verma
- grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India ,grid.418099.dNational Physical Laboratory, Council of Scientific and Industrial Research, Dr. K S Krishnan Road, New Delhi, 110012 India
| | - Reena Yadav
- grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India ,grid.418099.dNational Physical Laboratory, Council of Scientific and Industrial Research, Dr. K S Krishnan Road, New Delhi, 110012 India
| | - Animesh Pandey
- grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India ,grid.418099.dNational Physical Laboratory, Council of Scientific and Industrial Research, Dr. K S Krishnan Road, New Delhi, 110012 India
| | - Mandeep Kaur
- grid.418099.dNational Physical Laboratory, Council of Scientific and Industrial Research, Dr. K S Krishnan Road, New Delhi, 110012 India
| | - Sudhir Husale
- grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India ,grid.418099.dNational Physical Laboratory, Council of Scientific and Industrial Research, Dr. K S Krishnan Road, New Delhi, 110012 India
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24
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Coupled ferroelectricity and superconductivity in bilayer T d-MoTe 2. Nature 2023; 613:48-52. [PMID: 36600069 DOI: 10.1038/s41586-022-05521-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 11/03/2022] [Indexed: 01/05/2023]
Abstract
Achieving electrostatic control of quantum phases is at the frontier of condensed matter research. Recent investigations have revealed superconductivity tunable by electrostatic doping in twisted graphene heterostructures and in two-dimensional semimetals such as WTe2 (refs. 1-5). Some of these systems have a polar crystal structure that gives rise to ferroelectricity, in which the interlayer polarization exhibits bistability driven by external electric fields6-8. Here we show that bilayer Td-MoTe2 simultaneously exhibits ferroelectric switching and superconductivity. Notably, a field-driven, first-order superconductor-to-normal transition is observed at its ferroelectric transition. Bilayer Td-MoTe2 also has a maximum in its superconducting transition temperature (Tc) as a function of carrier density and temperature, allowing independent control of the superconducting state as a function of both doping and polarization. We find that the maximum Tc is concomitant with compensated electron and hole carrier densities and vanishes when one of the Fermi pockets disappears with doping. We argue that this unusual polarization-sensitive two-dimensional superconductor is driven by an interband pairing interaction associated with nearly nested electron and hole Fermi pockets.
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25
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Talantsev EF. The Compliance of the Upper Critical Field in Magic-Angle Multilayer Graphene with the Pauli Limit. MATERIALS (BASEL, SWITZERLAND) 2022; 16:256. [PMID: 36614595 PMCID: PMC9822272 DOI: 10.3390/ma16010256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/10/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
The Pauli limiting field represents a fundamental magnetic field at which the superconducting state collapses due to the spin-paramagnetic Cooper pair-breaking effect. Cao et al. (Nature 2021, 595, 526) reported that the magic-angle twisted trilayer graphene (MATNG, N = 3) exhibits the upper critical field which exceeds the Pauli limiting field by two to three times. This observation was interpreted as a violation of the Pauli-limiting field in MAT3G. Similar conclusions were recently reported by the same research group in MATNG (N = 4, 5) superlattices (Park, J.M. et al. Nat. Mater.2022, 21, 877). Here, we point out that Cao et al. (Nature 2021, 595, 526) calculated the Pauli limiting field by the use of reduced form (to the weak-coupling limit) of full equation of the theory of the electron−phonon-mediated superconductivity. Considering that in the same paper, Cao et al. (Nature 2021, 595, 526) reported that MATNGs are strong coupled superconductors, we calculate the Pauli limiting field for a strong coupled case and show that the observed upper critical fields in MATNGs comply with the Pauli limit. This implies that there is no violation of the Pauli limiting field in the Moiré multilayer graphene superlattices.
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Affiliation(s)
- Evgueni F Talantsev
- M. N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St., 620108 Ekaterinburg, Russia
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26
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Iurov A, Zhemchuzhna L, Gumbs G, Huang D, Tse WK, Blaise K, Ejiogu C. Floquet engineering of tilted and gapped Dirac bandstructure in 1T[Formula: see text]-MoS[Formula: see text]. Sci Rep 2022; 12:21348. [PMID: 36494457 PMCID: PMC9734163 DOI: 10.1038/s41598-022-25898-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
We have developed a rigorous theoretical formalism for Floquet engineering, investigating, and subsequently tailoring most crucial electronic properties of 1T[Formula: see text]-MoS[Formula: see text] by applying an external high-frequency dressing field within the off-resonance regime. It was recently demonstrated that monolayer semiconducting 1T[Formula: see text]-MoS[Formula: see text] exhibits tunable and gapped spin- and valley-polarized tilted Dirac bands. The electron-photon dressed states depend strongly on the polarization of the applied irradiation and reflect a full complexity of the low-energy Hamiltonian for non-irradiated material. We have calculated and analyzed the properties of the electron dressed states corresponding to linear and circular polarization of a dressing field by focusing on their symmetry, anisotropy, tilting, direct and indirect band gaps. Circularly polarized dressing field is known for transition into a new electronic state with broken time-reversal symmetry and a non-zero Chern number, and therefore, the combination of these topologically non-trivial phases and transitions between them could reveal some truly unique and previously unknown phenomena and applications. We have also computed and discussed the density of states for various types of 1T[Formula: see text]-MoS[Formula: see text] materials and its modification in the presence of a dressing field.
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Affiliation(s)
- Andrii Iurov
- Department of Physics and Computer Science, Medgar Evers College of City University of New York, Brooklyn, NY 11225 USA
| | - Liubov Zhemchuzhna
- Department of Physics and Computer Science, Medgar Evers College of City University of New York, Brooklyn, NY 11225 USA
- Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York, 10065 USA
| | - Godfrey Gumbs
- Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York, 10065 USA
- Donostia International Physics Center (DIPC), P de Manuel Lardizabal, 4, 20018 San Sebastian, Basque Country Spain
| | - Danhong Huang
- US Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico, 87117 USA
| | - Wang-Kong Tse
- Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, AL 35487 USA
| | - Kathy Blaise
- Department of Physics and Computer Science, Medgar Evers College of City University of New York, Brooklyn, NY 11225 USA
| | - Chinedu Ejiogu
- Department of Physics and Computer Science, Medgar Evers College of City University of New York, Brooklyn, NY 11225 USA
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27
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Dong Z, Guo W, Zhang L, Zhang Y, Chen J, Huang L, Chen C, Yang L, Ren Z, Zhang J, Yu W, Li J, Wang L, Zhang K. Excitonic Insulator Enabled Ultrasensitive Terahertz Photodetection with Efficient Low-Energy Photon Harvesting. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2204580. [PMID: 36354190 PMCID: PMC9798984 DOI: 10.1002/advs.202204580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/29/2022] [Indexed: 06/11/2023]
Abstract
Despite the interest toward the terahertz (THz) rapidly increasing, the high-efficient detection of THz photon is not widely available due to the low photoelectric conversion efficiency at this low-energy photon regime. Excitonic insulator (EI) states in emerging materials with anomalous optical transitions and renormalized valence band dispersions render their nontrivial photoresponse, which offers the prospect of harnessing the novel EI properties for the THz detection. Here, an EI-based photodetector is developed for efficient photoelectric conversion in the THz band. High-quality EI material Ta2 NiSe5 is synthesized and the existence of the EI state at room temperature is confirmed. The THz scanning near-field optical microscopy experimentally reveals the strong light-matter interaction in the THz band of EI state in the Ta2 NiSe5 . Benefiting from the strong light-matter interaction, the Ta2 NiSe5 -based photodetectors exhibit superior THz detection performances with a detection sensitivity of ≈42 pW Hz-1/2 and a response time of ≈1.1 µs at 0.1 THz at room temperature. This study provides a new avenue for realizing novel high-performance THz photodetectors by exploiting the emerging EI materials.
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Affiliation(s)
- Zhuo Dong
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
- School of Nano‐Tech and Nano‐BionicsUniversity of Science and Technology of ChinaJinzhai Road 96HefeiAnhui230026P. R. China
| | - Wanlong Guo
- State Key Laboratory for Infrared PhysicsShanghai Institute of Technical PhysicsChinese Academy of Sciences500 Yu‐tian RoadShanghai200083P. R. China
| | - Libo Zhang
- State Key Laboratory for Infrared PhysicsShanghai Institute of Technical PhysicsChinese Academy of Sciences500 Yu‐tian RoadShanghai200083P. R. China
| | - Yan Zhang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
- School of Nano‐Tech and Nano‐BionicsUniversity of Science and Technology of ChinaJinzhai Road 96HefeiAnhui230026P. R. China
| | - Jie Chen
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
| | - Luyi Huang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
| | - Cheng Chen
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
- School of Nano‐Tech and Nano‐BionicsUniversity of Science and Technology of ChinaJinzhai Road 96HefeiAnhui230026P. R. China
| | - Liu Yang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
- School of Nano‐Tech and Nano‐BionicsUniversity of Science and Technology of ChinaJinzhai Road 96HefeiAnhui230026P. R. China
| | - Zeqian Ren
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
| | - Junrong Zhang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
- School of Nano‐Tech and Nano‐BionicsUniversity of Science and Technology of ChinaJinzhai Road 96HefeiAnhui230026P. R. China
| | - Wenzhi Yu
- Songshan Lake Materials LaboratoryDongguanGuangdong523000P. R. China
| | - Jie Li
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
| | - Lin Wang
- State Key Laboratory for Infrared PhysicsShanghai Institute of Technical PhysicsChinese Academy of Sciences500 Yu‐tian RoadShanghai200083P. R. China
| | - Kai Zhang
- CAS Key Laboratory of Nanophotonic Materials and Devices & Key Laboratory of Nanodevices and Applicationsi‐LabSuzhou Institute of Nano‐Tech and Nano‐Bionics (SINANO)Chinese Academy of SciencesRuoshui Road 398SuzhouJiangsu215123P. R. China
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28
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Cho S, Huh S, Fang Y, Hua C, Bai H, Jiang Z, Liu Z, Liu J, Chen Z, Fukushima Y, Harasawa A, Kawaguchi K, Shin S, Kondo T, Lu Y, Mu G, Huang F, Shen D. Direct Observation of the Topological Surface State in the Topological Superconductor 2M-WS 2. NANO LETTERS 2022; 22:8827-8834. [PMID: 36367457 DOI: 10.1021/acs.nanolett.2c02372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The quantum spin Hall (QSH) effect has attracted extensive research interest because of the potential applications in spintronics and quantum computing, which is attributable to two conducting edge channels with opposite spin polarization and the quantized electronic conductance of 2e2/h. Recently, 2M-WS2, a new stable phase of transition metal dichalcogenides with a 2M structure showing a layer configuration identical to that of the monolayer 1T' TMDs, was suggested to be a QSH insulator as well as a superconductor with a critical transition temperature of around 8 K. Here, high-resolution angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES are applied to investigate the electronic and spin structure of the topological surface states (TSS) in the superconducting 2M-WS2. The TSS exhibit characteristic spin-momentum-locking behavior, suggesting the existence of long-sought nontrivial Z2 topological states therein. We expect that 2M-WS2 with coexisting superconductivity and TSS might host the promising Majorana bound states.
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Affiliation(s)
- Soohyun Cho
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai200050, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing100049, People's Republic of China
| | - Soonsang Huh
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba277-8581, Japan
| | - Yuqiang Fang
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai200050, People's Republic of China
- State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing100871, People's Republic of China
| | - Chenqiang Hua
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou310027, People's Republic of China
| | - Hua Bai
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou310027, People's Republic of China
| | - Zhicheng Jiang
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai200050, People's Republic of China
| | - Zhengtai Liu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai200050, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing100049, People's Republic of China
| | - Jishan Liu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai200050, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing100049, People's Republic of China
| | - Zhenhua Chen
- Shanghai Synchrotron Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201204, People's Republic of China
| | - Yuto Fukushima
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba277-8581, Japan
| | - Ayumi Harasawa
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba277-8581, Japan
| | - Kaishu Kawaguchi
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba277-8581, Japan
| | - Shik Shin
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba277-8581, Japan
| | - Takeshi Kondo
- Trans-Scale Quantum Science Institute, The University of Tokyo, Bunkyo-ku, Tokyo113-0033, Japan
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba277-8581, Japan
| | - Yunhao Lu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou310027, People's Republic of China
| | - Gang Mu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai200050, People's Republic of China
| | - Fuqiang Huang
- State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai200050, People's Republic of China
- State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing100871, People's Republic of China
| | - Dawei Shen
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai200050, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing100049, People's Republic of China
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Zhang G, Wu H, Zhang L, Yang L, Xie Y, Guo F, Li H, Tao B, Wang G, Zhang W, Chang H. Two-Dimensional Van Der Waals Topological Materials: Preparation, Properties, and Device Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2204380. [PMID: 36135779 DOI: 10.1002/smll.202204380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/23/2022] [Indexed: 06/16/2023]
Abstract
Over the past decade, 2D van der Waals (vdW) topological materials (TMs), including topological insulators and topological semimetals, which combine atomically flat 2D layers and topologically nontrivial band structures, have attracted increasing attention in condensed-matter physics and materials science. These easily cleavable and integrated TMs provide the ideal platform for exploring topological physics in the 2D limit, where new physical phenomena may emerge, and represent a potential to control and investigate exotic properties and device applications in nanoscale topological phases. However, multifaced efforts are still necessary, which is the prerequisite for the practical application of 2D vdW TMs. Herein, this review focuses on the preparation, properties, and device applications of 2D vdW TMs. First, three common preparation strategies for 2D vdW TMs are summarized, including single crystal exfoliation, chemical vapor deposition, and molecular beam epitaxy. Second, the origin and regulation of various properties of 2D vdW TMs are introduced, involving electronic properties, transport properties, optoelectronic properties, thermoelectricity, ferroelectricity, and magnetism. Third, some device applications of 2D vdW TMs are presented, including field-effect transistors, memories, spintronic devices, and photodetectors. Finally, some significant challenges and opportunities for the practical application of 2D vdW TMs in 2D topological electronics are briefly addressed.
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Affiliation(s)
- Gaojie Zhang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hao Wu
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Liang Zhang
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Li Yang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yuanmiao Xie
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Fei Guo
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Hongda Li
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Boran Tao
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Guofu Wang
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Microelectronics and Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Wenfeng Zhang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Shenzhen R&D Center of Huazhong University of Science and Technology (HUST), Shenzhen, 518000, China
| | - Haixin Chang
- Quantum-Nano Matter and Device Lab, Center for Joining and Electronic Packaging, State Key Laboratory of Material Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
- Shenzhen R&D Center of Huazhong University of Science and Technology (HUST), Shenzhen, 518000, China
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30
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Zhao A, Gu Q, Haugan TJ, Bullard TJ, Klemm RA. Type-II quantum spin Hall effect in two-dimensional metals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:485302. [PMID: 36191563 DOI: 10.1088/1361-648x/ac9720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 10/03/2022] [Indexed: 06/16/2023]
Abstract
The quantum spin Hall (QSH) effect has been observed in topological insulators and long quantum wells using spin-orbit coupling as the probe, but it has not yet been observed in a metal. An experiment is proposed to measure the different Type-II QSH effect of an electron or hole in a two-dimensional (2D) metal by using the previously unexplored but relativistically gauge-invariant form of the generated 2D QSH Hamiltonian. Instead of using the electric field in the surface of the spin-polarized bands of a topological insulator or across the quantum well width as the probe, ones uses an applied azimuthal vector potential and an applied radial electric field as the tools to generate a spontaneously quantized spin current in an otherwise spin unpolarized 2D metal. A long cylindrical solenoid lies normally through the inner radius of a 2D metallic Corbino disk. The currentISsurrounding the solenoid produces an azimuthal magnetic vector potential but no magnetic field in the disk. In addition, a radial electric field is generated across the disk by imposing either a potential differenceΔvor a radial charge currentIacross its inner and outer radii. Combined changes inISand in eitherΔvorIgenerate spontaneously quantized azimuthal charge and spin currents. The experiment is designed to measure these quantized azimuthal charge and spin currents in the disk consistently. The quantum Hamiltonians for both experiments are solved exactly. A method to control the Joule heating is presented, which could potentially allow the Type-II QSH measurements to be made at room temperature.
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Affiliation(s)
- Aiying Zhao
- Institute of Theoretical Physics, University of Science and Technology Beijing, Beijing 100083, People's Republic of China
- Department of Physics, University of Central Florida, Orlando, FL 32816-2385, United States of America
| | - Qiang Gu
- Institute of Theoretical Physics, University of Science and Technology Beijing, Beijing 100083, People's Republic of China
| | - Timothy J Haugan
- U. S. Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433-7251, United States of America
| | - Thomas J Bullard
- U. S. Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433-7251, United States of America
| | - Richard A Klemm
- Department of Physics, University of Central Florida, Orlando, FL 32816-2385, United States of America
- U. S. Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433-7251, United States of America
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31
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Hu H, Chen N, Teng H, Yu R, Qu Y, Sun J, Xue M, Hu D, Wu B, Li C, Chen J, Liu M, Sun Z, Liu Y, Li P, Fan S, García de Abajo FJ, Dai Q. Doping-driven topological polaritons in graphene/α-MoO 3 heterostructures. NATURE NANOTECHNOLOGY 2022; 17:940-946. [PMID: 35982316 PMCID: PMC9477736 DOI: 10.1038/s41565-022-01185-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 06/28/2022] [Indexed: 05/20/2023]
Abstract
Control over charge carrier density provides an efficient way to trigger phase transitions and modulate the optoelectronic properties of materials. This approach can also be used to induce topological transitions in the optical response of photonic systems. Here we report a topological transition in the isofrequency dispersion contours of hybrid polaritons supported by a two-dimensional heterostructure consisting of graphene and α-phase molybdenum trioxide. By chemically changing the doping level of graphene, we observed that the topology of polariton isofrequency surfaces transforms from open to closed shapes as a result of doping-dependent polariton hybridization. Moreover, when the substrate was changed, the dispersion contour became dominated by flat profiles at the topological transition, thus supporting tunable diffractionless polariton propagation and providing local control over the optical contour topology. We achieved subwavelength focusing of polaritons down to 4.8% of the free-space light wavelength by using a 1.5-μm-wide silica substrate as an in-plane lens. Our findings could lead to on-chip applications in nanoimaging, optical sensing and manipulation of energy transfer at the nanoscale.
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Grants
- National Key Research and Development Program of China (Grant No. 2020YFB2205701), the National Natural Science Foundation of China (Grant Nos. 51902065, 52172139, 51925203, U2032206, 52072083, and 51972072)
- Beijing Municipal Natural Science Foundation (Grant No. 2202062), and Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB36000000, XDB30000000).
- Z.P.S. acknowledges the Academy of Finland (Grant Nos. 314810, 333982, 336144, and 336818), The Business Finland (ALDEL), the Academy of Finland Flagship Programme (320167, PREIN), the European Union’s Horizon 2020 research and innovation program (820423, S2QUIP; 965124, FEMTOCHIP), the EU H2020-MSCA-RISE-872049 (IPN-Bio), and the ERC (834742).
- P.N.L acknowledges the National Natural Science Foundation of China (grantno.62075070)
- S.F. acknowledges the support of the U.S. Department of Energy under Grant No. DE-FG02-07ER46426.
- F.J.G.A. acknowledges the ERC (Advanced Grant 789104-eNANO), the Spanish MINECO (SEV2015-0522), and the CAS President’s International Fellowship Initiative (PIFI) for 2021.
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Affiliation(s)
- Hai Hu
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, People's Republic of China.
- University of Chinese Academy of Sciences, Beijing, People's Republic of China.
| | - Na Chen
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Hanchao Teng
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Renwen Yu
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain.
- Department of Electrical Engineering, Ginzton Laboratory, Stanford University, Stanford, CA, USA.
| | - Yunpeng Qu
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Jianzhe Sun
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Beijing, People's Republic of China
| | - Mengfei Xue
- The Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Debo Hu
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Bin Wu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Beijing, People's Republic of China
| | - Chi Li
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Jianing Chen
- The Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Mengkun Liu
- Department of Physics and Astronomy, Stony Brook University, NY, USA
| | - Zhipei Sun
- Department of Electronics and Nanoengineering, Aalto University, Espoo, Finland
| | - Yunqi Liu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Beijing, People's Republic of China
| | - Peining Li
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Shanhui Fan
- Department of Electrical Engineering, Ginzton Laboratory, Stanford University, Stanford, CA, USA
| | - F Javier García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain.
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain.
| | - Qing Dai
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, People's Republic of China.
- University of Chinese Academy of Sciences, Beijing, People's Republic of China.
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32
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Li L, Zhang S, Hu G, Guo L, Wei T, Qin W, Xiang B, Zeng C, Zhang Z, Cui P. Converting a Monolayered NbSe 2 into an Ising Superconductor with Nontrivial Band Topology via Physical or Chemical Pressuring. NANO LETTERS 2022; 22:6767-6774. [PMID: 35930622 DOI: 10.1021/acs.nanolett.2c02422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Two-dimensional transition metal dichalcogenides possessing superconductivity and strong spin-orbit coupling exhibit high in-plane upper critical fields due to Ising pairing. Yet to date, whether such systems can become topological Ising superconductors remains to be materialized. Here we show that monolayered NbSe2 can be converted into Ising superconductors with nontrivial band topology via physical or chemical pressuring. Using first-principles calculations, we first demonstrate that a hydrostatic pressure higher than 2.5 GPa can induce a p-d band inversion, rendering nontrivial band topology to NbSe2. We then illustrate that Te-doping can function as chemical pressuring in inducing nontrivial topology in NbSe2-xTex with x ≥ 0.8, due to a larger atomic radius and stronger spin-orbit coupling of Te. We also evaluate the upper critical fields within both approaches, confirming the enhanced Ising superconductivity nature, as experimentally observed. Our findings may prove to be instrumental in material realization of topological Ising superconductivity in two-dimensional systems.
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Affiliation(s)
- Leiqiang Li
- International Center for Quantum Design of Functional Materials (ICQD), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shunhong Zhang
- International Center for Quantum Design of Functional Materials (ICQD), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Guojing Hu
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Linhai Guo
- International Center for Quantum Design of Functional Materials (ICQD), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Tong Wei
- International Center for Quantum Design of Functional Materials (ICQD), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wei Qin
- Department of Physics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Bin Xiang
- Department of Materials Science & Engineering, CAS Key Lab of Materials for Energy Conversion, Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Changgan Zeng
- International Center for Quantum Design of Functional Materials (ICQD), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Zhenyu Zhang
- International Center for Quantum Design of Functional Materials (ICQD), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Ping Cui
- International Center for Quantum Design of Functional Materials (ICQD), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
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33
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Lüpke F, Waters D, Pham AD, Yan J, Mandrus DG, Ganesh P, Hunt BM. Quantum Spin Hall Edge States and Interlayer Coupling in Twisted Bilayer WTe 2. NANO LETTERS 2022; 22:5674-5680. [PMID: 35759639 DOI: 10.1021/acs.nanolett.2c00432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The quantum spin Hall (QSH) effect, characterized by topologically protected spin-polarized edge states, was recently demonstrated in monolayers of the transition metal dichalcogenide (TMD) WTe2. However, the robustness of this topological protection remains largely unexplored in van der Waals heterostructures containing one or more layers of a QSH insulator. In this work, we use scanning tunneling microscopy and spectroscopy (STM/STS) to explore the topological nature of twisted bilayer (tBL) WTe2. At the tBL edges, we observe the characteristic spectroscopic signatures of the QSH edge states. For small twist angles, a rectangular moiré pattern develops, which results in local modifications of the band structure. Using first-principles calculations, we quantify the interactions in tBL WTe2 and its topological edge states as a function of interlayer distance and conclude that it is possible to engineer the topology of WTe2 bilayers via the twist angle as well as interlayer interactions.
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Affiliation(s)
- Felix Lüpke
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Dacen Waters
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Department of Physics, University of Washington, Seattle, Washington 98195, United States
| | - Anh D Pham
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jiaqiang Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - David G Mandrus
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Panchapakesan Ganesh
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Benjamin M Hunt
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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34
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Wang M, Kumar A, Dong H, Woods JM, Pondick JV, Xu S, Hynek DJ, Guo P, Qiu DY, Cha JJ. A Gapped Phase in Semimetallic T d -WTe 2 Induced by Lithium Intercalation. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2200861. [PMID: 35488783 DOI: 10.1002/adma.202200861] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/20/2022] [Indexed: 06/14/2023]
Abstract
The Weyl semimetal WTe2 has shown several correlated electronic behaviors, such as the quantum spin Hall effect, superconductivity, ferroelectricity, and a possible exciton insulator state, all of which can be tuned by various physical and chemical approaches. Here, a new electronic phase in WTe2 induced by lithium intercalation is discovered. The new phase exhibits an increasing resistivity with decreasing temperature and its carrier density is almost two orders of magnitude lower than the carrier density of the semimetallic Td phase, probed by in situ Hall measurements as a function of lithium intercalation. The theoretical calculations predict the new lithiated phase to be a potential charge density wave (CDW) phase with a bandgap of ≈0.14 eV, in good agreement with the in situ transport data. The new phase is structurally distinct from the initial Td phase, characterized by polarization-angle-dependent Raman spectroscopy, and large lattice distortions close to 6% are predicted in the new phase. This finding of a new gapped phase in a 2D semimetal demonstrates electrochemical intercalation as a powerful tuning knob for modulating electron density and phase stability in 2D materials.
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Affiliation(s)
- Mengjing Wang
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA
| | - Aakash Kumar
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA
| | - Hao Dong
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, 06511, USA
| | - John M Woods
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA
| | - Joshua V Pondick
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA
| | - Shiyu Xu
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA
| | - David J Hynek
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA
| | - Peijun Guo
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, 06511, USA
| | - Diana Y Qiu
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA
| | - Judy J Cha
- Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA
- Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA
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35
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Zhao C, Li L, Zhang L, Qin J, Chen H, Xia B, Yang B, Zheng H, Wang S, Liu C, Li Y, Guan D, Cui P, Zhang Z, Jia J. Coexistence of Robust Edge States and Superconductivity in Few-Layer Stanene. PHYSICAL REVIEW LETTERS 2022; 128:206802. [PMID: 35657877 DOI: 10.1103/physrevlett.128.206802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 03/31/2022] [Indexed: 06/15/2023]
Abstract
High-quality stanene films have been actively pursued for realizing not only quantum spin Hall edge states without backscattering, but also intrinsic superconductivity, two central ingredients that may further endow the systems to host topological superconductivity. Yet to date, convincing evidence of topological edge states in stanene remains to be seen, let alone the coexistence of these two ingredients, owing to the bottleneck of growing high-quality stanene films. Here we fabricate one- to five-layer stanene films on the Bi(111) substrate and observe the robust edge states using scanning tunneling microscopy/spectroscopy. We also measure distinct superconducting gaps on different-layered stanene films. Our first-principles calculations further show that hydrogen passivation plays a decisive role as a surfactant in improving the quality of the stanene films, while the Bi substrate endows the films with nontrivial topology. The coexistence of nontrivial topology and intrinsic superconductivity renders the system a promising candidate to become the simplest topological superconductor based on a single-element system.
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Affiliation(s)
- Chenxiao Zhao
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Leiqiang Li
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Liying Zhang
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, School of Materials Science and Engineering, Henan University, Kaifeng 475004, China
- International Laboratory for Quantum Functional Materials of Henan and School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, China
| | - Jin Qin
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hongyuan Chen
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bing Xia
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bo Yang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hao Zheng
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Shiyong Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Canhua Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yaoyi Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Dandan Guan
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ping Cui
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhenyu Zhang
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jinfeng Jia
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
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Deng J, Zhang W, Dai X, Yu Y, Li Z, Wang W, Wang L, Zhou J, Chen X. Nonmonotonic wavelength dependence of the polarization-sensitive infrared photoresponse of an anisotropic semimetal. NANOSCALE 2022; 14:7314-7321. [PMID: 35532931 DOI: 10.1039/d1nr08268j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Layered semimetals with in-plane anisotropy are promising for advanced polarization-sensitive infrared detection. The investigation of the polarization-dependent photoresponse of semimetals over the whole visible-to-long-wave-infrared range and revealing the physical connection between their optoelectronic properties, optical properties, and electronic band structures is required, but there have been very few studies of this kind. In this work, we conducted a thorough investigation on the polarization-dependent infrared photoresponse of WTe2 over the visible-to-long-wave-infrared range and discovered a textbook-like perfect consistency between the wavelength-dependent polarization-sensitive photoresponse and the anisotropic dielectric constant mainly affected by interband transitions near the Weyl point. It is revealed that the polarization sensitivity and the responsivity both vary non-monotonically with the wavelength. This phenomenon is attributed to the polarization selective excitation of interband transitions associated with asymmetrically distributed electron orbitals around the Weyl points. Concerning the infrared detection properties of WTe2, a maximum responsivity of 0.68 mA W-1 is obtained under self-powered operation. The power dependence of the photoresponse is linear, and the response time is around 14 μs. This work would provoke further studies about the anisotropic photoresponse associated with the transitions even closer to the Dirac or Weyl points, and it provides an approach to select the right semimetal for the right wavelength range of infrared polarization detection.
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Affiliation(s)
- Jie Deng
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Zhang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, Nanjing 211816, China.
| | - Xu Dai
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu Yu
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China.
| | - Zhifeng Li
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Wang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, Nanjing 211816, China.
| | - Lin Wang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, Nanjing 211816, China.
| | - Jing Zhou
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoshuang Chen
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
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Rasche B, Brunner J, Schramm T, Ghimire MP, Nitzsche U, Büchner B, Giraud R, Richter M, Dufouleur J. Determination of Cleavage Energy and Efficient Nanostructuring of Layered Materials by Atomic Force Microscopy. NANO LETTERS 2022; 22:3550-3556. [PMID: 35427144 DOI: 10.1021/acs.nanolett.1c04868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A method is presented to use atomic force microscopy to measure the cleavage energy of van der Waals materials and similar quasi-two-dimensional materials. The cleavage energy of graphite is measured to be 0.36 J/m2, in good agreement with literature data. The same method yields a cleavage energy of 0.6 J/m2 for MoS2 as a representative of the dichalcogenides. In the case of the weak topological insulator Bi14Rh3I9 no cleavage energy is obtained, although cleavage is successful with an adapted approach. The cleavage energies of these materials are evaluated by means of density-functional calculations and literature data. This further validates the presented method and sets an upper limit of about 0.7 J/m2 to the cleavage energy that can be measured by the present setup. In addition, this method can be used as a tool for manipulating exfoliated flakes, prior to or after contacting, which may open a new route for the fabrication of nanostructures.
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Affiliation(s)
- Bertold Rasche
- Department of Chemistry, University of Cologne, 50939 Cologne, Germany
| | - Julius Brunner
- Leibniz IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden, Germany
| | - Tim Schramm
- Leibniz IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden, Germany
| | - Madhav Prasad Ghimire
- Central Department of Physics, Tribhuvan University, Kirtipur 44613, Kathmandu, Nepal
| | - Ulrike Nitzsche
- Leibniz IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden, Germany
| | - Bernd Büchner
- Leibniz IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden, Germany
- Department of Physics, TU Dresden, D-01062 Dresden, Germany
| | - Romain Giraud
- Leibniz IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden, Germany
- Université Grenoble Alpes, CNRS, CEA, Grenoble-INP, Spintec, F-38000 Grenoble, France
| | - Manuel Richter
- Leibniz IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden, Germany
- Dresden Center for Computational Materials Science (DCMS), TU Dresden, D-01062 Dresden, Germany
| | - Joseph Dufouleur
- Leibniz IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden, Germany
- Center for Transport and Devices, TU Dresden, D-01062 Dresden, Germany
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38
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One-dimensional Luttinger liquids in a two-dimensional moiré lattice. Nature 2022; 605:57-62. [PMID: 35508779 DOI: 10.1038/s41586-022-04514-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 02/03/2022] [Indexed: 11/08/2022]
Abstract
The Luttinger liquid (LL) model of one-dimensional (1D) electronic systems provides a powerful tool for understanding strongly correlated physics, including phenomena such as spin-charge separation1. Substantial theoretical efforts have attempted to extend the LL phenomenology to two dimensions, especially in models of closely packed arrays of 1D quantum wires2-13, each being described as a LL. Such coupled-wire models have been successfully used to construct two-dimensional (2D) anisotropic non-Fermi liquids2-6, quantum Hall states7-9, topological phases10,11 and quantum spin liquids12,13. However, an experimental demonstration of high-quality arrays of 1D LLs suitable for realizing these models remains absent. Here we report the experimental realization of 2D arrays of 1D LLs with crystalline quality in a moiré superlattice made of twisted bilayer tungsten ditelluride (tWTe2). Originating from the anisotropic lattice of the monolayer, the moiré pattern of tWTe2 hosts identical, parallel 1D electronic channels, separated by a fixed nanoscale distance, which is tuneable by the interlayer twist angle. At a twist angle of approximately 5 degrees, we find that hole-doped tWTe2 exhibits exceptionally large transport anisotropy with a resistance ratio of around 1,000 between two orthogonal in-plane directions. The across-wire conductance exhibits power-law scaling behaviours, consistent with the formation of a 2D anisotropic phase that resembles an array of LLs. Our results open the door for realizing a variety of correlated and topological quantum phases based on coupled-wire models and LL physics.
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Abstract
We present a mechanism for unconventional superconductivity in doped band insulators, where short-ranged pairing interaction arises from Coulomb repulsion due to virtual interband or excitonic processes. Remarkably, electron pairing is found upon infinitesimal doping, giving rise to Bose–Einstein condensate (BEC)–Bardeen–Cooper–Schrieffer (BCS) crossover at low density. Our theory explains puzzling behaviors of superconductivity and predicts spin-triplet pairing in electron-doped ZrNCl and WTe2. Despite being of fundamental importance and potential interest for topological quantum computing, spin-triplet superconductors remain rare in solid state materials after decades of research. In this work, we present a three-particle mechanism for spin-triplet superconductivity in multiband systems, where an effective attraction between doped electrons is produced from the Coulomb repulsion via a virtual interband transition involving a third electron [V. Crépel, L. Fu, Sci. Adv. 7, eabh2233 (2021)]. Our theory is analytically controlled by an interband hybridization parameter and explicitly demonstrated in doped band insulators with the example of an extended Hubbard model. Our theory of exciton-mediated pairing reveals how, as a matter of principle, a two-particle bound state can arise from the strong electron repulsion upon doping, opening a viable path to Bose–Einstein condensate (BEC)–Bardeen–Cooper–Schrieffer (BCS) physics in solid state systems. In light of this theory, we propose that recently discovered dilute superconductors such as ZrNCl, WTe2, and moiré materials can be spin-triplet and compare the expected consequences of our theory with experimental data.
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40
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Alsharari AM, Ulloa SE. Inducing chiral superconductivity on honeycomb lattice systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:205403. [PMID: 35235911 DOI: 10.1088/1361-648x/ac5a03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 03/02/2022] [Indexed: 06/14/2023]
Abstract
Superconductivity in graphene-based systems has recently attracted much attention, as either intrinsic behavior or induced by proximity to a superconductor may lead to interesting topological phases and symmetries of the pairing function. A prominent system considers the pairing to have chiral symmetry. The question arises as to the effect of possible spin-orbit coupling on the resulting superconducting quasiparticle (QP) spectrum. Utilizing a Bogolyubov-de Gennes (BdG) Hamiltonian, we explore the interplay of different interaction terms in the system, and their role in generating complex Berry curvatures in the QP spectrum, as well as non-trivial topological behavior. We demonstrate that the topology of the BdG Hamiltonian in these systems may result in the appearance of edge states along the zigzag edges of nanoribbons in the appropriate regime. For suitable chemical potential and superconducting pairing strength, we find the appearance of robust midgap states at zigzag edges, well protected by large excitation gaps and momentum transfer.
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Affiliation(s)
| | - Sergio E Ulloa
- Department of Physics and Astronomy, and Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, OH 45701, United States of America
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
- Center for Nanostructured Graphene, DTU Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
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41
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Zhou G, Gao H, Li J, He X, He Y, Li Y, Hao G. Water-assisted controllable growth of atomically thin WTe 2nanoflakes by chemical vapor deposition based on precursor design and substrate engineering strategies. NANOTECHNOLOGY 2022; 33:175602. [PMID: 35008075 DOI: 10.1088/1361-6528/ac49c4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
WTe2nanostructures have intrigued much attention due to their unique properties, such as large non-saturating magnetoresistance, quantum spin Hall effect and topological surface state. However, the controllable growth of large-area atomically thin WTe2nanostructures remains a significant challenge. In the present work, we demonstrate the controllable synthesis of 1T' atomically thin WTe2nanoflakes (NFs) by water-assisted ambient pressure chemical vapor deposition method based on precursor design and substrate engineering strategies. The introduction of water during the growth process can generate a new synthesized route by reacting with WO3to form intermediate volatile metal oxyhydroxide. Using WO3foil as the growth precursor can drastically enhance the uniformity of as-prepared large-area 1T' WTe2NFs compared to WO3powders. Moreover, highly oriented WTe2NFs with distinct orientations can be obtained by using a-plane and c-plane sapphire substrates, respectively. Corresponding precursor design and substrate engineering strategies are expected to be applicable to other low dimensional transition metal dichalcogenides, which are crucial for the design of novel electronic and optoelectronic devices.
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Affiliation(s)
- Guoliang Zhou
- School of Physics and Optoelectronics and and Hunan Key Laboratory for Micro-Nano Energy Materials and Device, Xiangtan University, Xiangtan 411105, People's Republic of China
- Hunan Institute of Advanced Sensing and Information Technology, Xiangtan University, Xiangtan 411105, People's Republic of China
| | - Hui Gao
- School of Physics and Optoelectronics and and Hunan Key Laboratory for Micro-Nano Energy Materials and Device, Xiangtan University, Xiangtan 411105, People's Republic of China
- Hunan Institute of Advanced Sensing and Information Technology, Xiangtan University, Xiangtan 411105, People's Republic of China
| | - Jin Li
- School of Physics and Optoelectronics and and Hunan Key Laboratory for Micro-Nano Energy Materials and Device, Xiangtan University, Xiangtan 411105, People's Republic of China
| | - Xiaoyue He
- Materials Growth and Characterization Center, Songshan Lake Materials Laboratory, Dongguan 523808, People's Republic of China
| | - Yanbing He
- School of Physics and Optoelectronics and and Hunan Key Laboratory for Micro-Nano Energy Materials and Device, Xiangtan University, Xiangtan 411105, People's Republic of China
- Hunan Institute of Advanced Sensing and Information Technology, Xiangtan University, Xiangtan 411105, People's Republic of China
| | - Yan Li
- School of Physics and Optoelectronics and and Hunan Key Laboratory for Micro-Nano Energy Materials and Device, Xiangtan University, Xiangtan 411105, People's Republic of China
- Hunan Institute of Advanced Sensing and Information Technology, Xiangtan University, Xiangtan 411105, People's Republic of China
| | - Guolin Hao
- School of Physics and Optoelectronics and and Hunan Key Laboratory for Micro-Nano Energy Materials and Device, Xiangtan University, Xiangtan 411105, People's Republic of China
- Hunan Institute of Advanced Sensing and Information Technology, Xiangtan University, Xiangtan 411105, People's Republic of China
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42
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Huang H, Zha J, Li S, Tan C. Two-dimensional alloyed transition metal dichalcogenide nanosheets: Synthesis and applications. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2021.06.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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43
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Azizi A, Dogan M, Cain JD, Lee K, Yu X, Shi W, Glazer EC, Cohen ML, Zettl A. Experimental and Theoretical Study of Possible Collective Electronic States in Exfoliable Re-Doped NbS 2. ACS NANO 2021; 15:18297-18304. [PMID: 34739204 DOI: 10.1021/acsnano.1c07526] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Metallic transition-metal dichalcogenides (TMDs) are rich material systems in which the interplay between strong electron-electron and electron-phonon interactions often results in a variety of collective electronic states, such as charge density waves (CDWs) and superconductivity. While most metallic group V TMDs exhibit coexisting superconducting and CDW phases, 2H-NbS2 stands out with no charge ordering. Further, due to strong interlayer interaction, the preparation of ultrathin samples of 2H-NbS2 has been challenging, limiting the exploration of presumably rich quantum phenomena in reduced dimensionality. Here, we demonstrate experimentally and theoretically that light substitutional doping of NbS2 with heavy atoms is an effective approach to modify both interlayer interaction and collective electronic states in NbS2. Very low concentrations of Re dopants (<1%) make NbS2 exfoliable (down to monolayer) while maintaining its 2H crystal structure and superconducting behavior. In addition, first-principles calculations suggest that Re dopants can stabilize some native CDW patterns that are not stable in pristine NbS2.
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Affiliation(s)
- Amin Azizi
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute at the University of California, Berkeley, Berkeley, California 94720, United States
| | - Mehmet Dogan
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Jeffrey D Cain
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute at the University of California, Berkeley, Berkeley, California 94720, United States
| | - Kyunghoon Lee
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute at the University of California, Berkeley, Berkeley, California 94720, United States
| | - Xuanze Yu
- Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, United States
| | - Wu Shi
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute at the University of California, Berkeley, Berkeley, California 94720, United States
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200438, China
| | - Emily C Glazer
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Marvin L Cohen
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
| | - Alex Zettl
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute at the University of California, Berkeley, Berkeley, California 94720, United States
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44
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Xie J, Liu X, Zhang W, Wong SM, Zhou X, Zhao Y, Wang S, Lai KT, Goh SK. Fragile Pressure-Induced Magnetism in FeSe Superconductors with a Thickness Reduction. NANO LETTERS 2021; 21:9310-9317. [PMID: 34714653 DOI: 10.1021/acs.nanolett.1c03508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The emergence of high transition temperature (Tc) superconductivity in bulk FeSe under pressure is associated with the tuning of nematicity and magnetism. However, sorting out the relative contributions from magnetic and nematic fluctuations to the enhancement of Tc remains challenging. Here, we design and conduct a series of high-pressure experiments on FeSe thin flakes. We find that as the thickness decreases the nematic phase boundary on temperature-pressure phase diagrams remains robust while the magnetic order is significantly weakened. A local maximum of Tc is observed outside the nematic phase region, not far from the extrapolated nematic end point in all samples. However, the maximum Tc value is reduced associated with the weakening of magnetism. No high-Tc phase is observed in the thinnest sample. Our results strongly suggest that nematic fluctuations alone can only have a limited effect while magnetic fluctuations are pivotal on the enhancement of Tc in FeSe.
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Affiliation(s)
- Jianyu Xie
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Xinyou Liu
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Wei Zhang
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Sum Ming Wong
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Xuefeng Zhou
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yusheng Zhao
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Shanmin Wang
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Kwing To Lai
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Swee K Goh
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
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45
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Tan C, Deng MX, Zheng G, Xiang F, Albarakati S, Algarni M, Farrar L, Alzahrani S, Partridge J, Yi JB, Hamilton AR, Wang RQ, Wang L. Spin-Momentum Locking Induced Anisotropic Magnetoresistance in Monolayer WTe 2. NANO LETTERS 2021; 21:9005-9011. [PMID: 34694117 DOI: 10.1021/acs.nanolett.1c02329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Monolayer WTe2 is predicted to be a quantum spin Hall insulator (QSHI), and its quantized edge transport has recently been demonstrated. However, one of the essential properties of a QSHI, spin-momentum locking of the helical edge states, has yet to be experimentally validated. Here, we measure and observe gate-controlled anisotropic magnetoresistance (AMR) in monolayer WTe2 devices. Electrically tuning the Fermi energy into the band gap, a large in-plane AMR is observed and the minimum of the in-plane AMR occurs when the applied magnetic field is perpendicular to the current direction. In line with the experimental observations, the theoretical predictions based on the band structure of monolayer WTe2 demonstrate that the AMR effect originates from spin-momentum locking in the helical edge states of monolayer WTe2. Our findings reveal that the spin quantization axis of the helical edge states in monolayer WTe2 can be precisely determined from AMR measurements.
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Affiliation(s)
- Cheng Tan
- School of Science and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, RMIT Node, RMIT University, Melbourne, Victoria 3000, Australia
| | - Ming-Xun Deng
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, SPTE, South China Normal University, Guangzhou 510006, China
| | - Guolin Zheng
- School of Science and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, RMIT Node, RMIT University, Melbourne, Victoria 3000, Australia
| | - Feixiang Xiang
- School of Physics and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, UNSW Node, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Sultan Albarakati
- School of Science and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, RMIT Node, RMIT University, Melbourne, Victoria 3000, Australia
| | - Meri Algarni
- School of Science and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, RMIT Node, RMIT University, Melbourne, Victoria 3000, Australia
| | - Lawrence Farrar
- School of Science and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, RMIT Node, RMIT University, Melbourne, Victoria 3000, Australia
| | - Saleh Alzahrani
- School of Science and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, RMIT Node, RMIT University, Melbourne, Victoria 3000, Australia
| | - James Partridge
- School of Science and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, RMIT Node, RMIT University, Melbourne, Victoria 3000, Australia
| | - Jia Bao Yi
- Global Innovative Center for Advanced Nanomaterials, School of Engineering, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Alex R Hamilton
- School of Physics and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, UNSW Node, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Rui-Qiang Wang
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, SPTE, South China Normal University, Guangzhou 510006, China
| | - Lan Wang
- School of Science and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, RMIT Node, RMIT University, Melbourne, Victoria 3000, Australia
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46
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Zhang D, Falson J. Ising pairing in atomically thin superconductors. NANOTECHNOLOGY 2021; 32:502003. [PMID: 34479228 DOI: 10.1088/1361-6528/ac238d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 09/03/2021] [Indexed: 06/13/2023]
Abstract
Ising-type pairing in atomically thin superconducting materials has emerged as a novel means of generating devices with resilience to a magnetic field applied parallel to the two-dimensional (2D) plane. In this mini-review, we canvas the state of the field by giving a historical account of 2D superconductors with strongly enhanced in-plane upper critical fields, together with the type-I and type-II Ising pairing mechanisms. We highlight the vital role of spin-orbit coupling in these superconductors and discuss other effects such as symmetry breaking, atomic thicknesses, etc. Finally, we summarize the recent theoretical proposals and highlight the open questions, such as exploring topological superconductivity in these systems and looking for more materials with Ising pairing.
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Affiliation(s)
- Ding Zhang
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Beijing Academy of Quantum Information Sciences, Beijing 100193, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
| | - Joseph Falson
- Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, CA, United States of America
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA 91125, United States of America
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47
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Jing R, Shao Y, Fei Z, Lo CFB, Vitalone RA, Ruta FL, Staunton J, Zheng WJC, Mcleod AS, Sun Z, Jiang BY, Chen X, Fogler MM, Millis AJ, Liu M, Cobden DH, Xu X, Basov DN. Terahertz response of monolayer and few-layer WTe 2 at the nanoscale. Nat Commun 2021; 12:5594. [PMID: 34552072 PMCID: PMC8458490 DOI: 10.1038/s41467-021-23933-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 05/17/2021] [Indexed: 02/08/2023] Open
Abstract
Tungsten ditelluride (WTe2) is an atomically layered transition metal dichalcogenide whose physical properties change systematically from monolayer to bilayer and few-layer versions. In this report, we use apertureless scattering-type near-field optical microscopy operating at Terahertz (THz) frequencies and cryogenic temperatures to study the distinct THz range electromagnetic responses of mono-, bi- and trilayer WTe2 in the same multi-terraced micro-crystal. THz nano-images of monolayer terraces uncovered weakly insulating behavior that is consistent with transport measurements. The near-field signal on bilayer regions shows moderate metallicity with negligible temperature dependence. Subdiffractional THz imaging data together with theoretical calculations involving thermally activated carriers favor the semimetal scenario with [Formula: see text] over the semiconductor scenario for bilayer WTe2. Also, we observed clear metallic behavior of the near-field signal on trilayer regions. Our data are consistent with the existence of surface plasmon polaritons in the THz range confined to trilayer terraces in our specimens. Finally, data for microcrystals up to 12 layers thick reveal how the response of a few-layer WTe2 asymptotically approaches the bulk limit.
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Affiliation(s)
- Ran Jing
- Department of Physics, Columbia University, New York, NY, USA.
| | - Yinming Shao
- Department of Physics, Columbia University, New York, NY, USA
| | - Zaiyao Fei
- Department of Physics, University of Washington, Seattle, WA, USA
| | | | | | - Francesco L Ruta
- Department of Physics, Columbia University, New York, NY, USA
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA
| | - John Staunton
- Department of Physics, Columbia University, New York, NY, USA
| | | | | | - Zhiyuan Sun
- Department of Physics, Columbia University, New York, NY, USA
| | - Bor-Yuan Jiang
- Department of Physics, University of California, San Diego, La Jolla, CA, USA
| | - Xinzhong Chen
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, USA
| | - Michael M Fogler
- Department of Physics, University of California, San Diego, La Jolla, CA, USA
| | - Andrew J Millis
- Department of Physics, Columbia University, New York, NY, USA
- Center for Computational Quantum Physics, Flatiron Institute, New York, NY, USA
| | - Mengkun Liu
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, USA
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - David H Cobden
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, WA, USA
- Department of Material Science and Engineering, University of Washington, Seattle, WA, USA
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, USA
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48
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Coexistence of resistance oscillations and the anomalous metal phase in a lithium intercalated TiSe 2 superconductor. Nat Commun 2021; 12:5342. [PMID: 34504094 PMCID: PMC8429654 DOI: 10.1038/s41467-021-25671-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 08/22/2021] [Indexed: 11/24/2022] Open
Abstract
Superconductivity and charge density wave (CDW) appear in the phase diagram of a variety of materials including the high-Tc cuprate family and many transition metal dichalcogenides (TMDs). Their interplay may give rise to exotic quantum phenomena. Here, we show that superconducting arrays can spontaneously form in TiSe2–a TMD with coexisting superconductivity and CDW—after lithium ion intercalation. We induce a superconducting dome in the phase diagram of LixTiSe2 by using the ionic solid-state gating technique. Around optimal doping, we observe magnetoresistance oscillations, indicating the emergence of periodically arranged domains. In the same temperature, magnetic field and carrier density regime where the resistance oscillations occur, we observe signatures for the anomalous metal—a state with a resistance plateau across a wide temperature range below the superconducting transition. Our study not only sheds further insight into the mechanism for the periodic electronic structure, but also reveals the interplay between the anomalous metal and superconducting fluctuations. The interplay between superconductivity and charge density wave (CDW) gives rise to exotic quantum phenomena. Here, the authors observe magnetoresistance oscillations and an anomalous metal state due to the coexistence of superconductivity and CDW in lithium intercalated TiSe2.
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49
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Gao J, Ding W, Zhang S, Zhang Z, Cui P. Coexistence of Superconductivity and Nontrivial Band Topology in Monolayered Cobalt Pnictides on SrTiO 3. NANO LETTERS 2021; 21:7396-7404. [PMID: 34431678 DOI: 10.1021/acs.nanolett.1c02830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
As an intrinsically layered material, FeSe has been extensively explored for potentially revealing the underlying mechanisms of high transition temperature (high-Tc) superconductivity and realizing topological superconductivity and Majorana zero modes. Here we use first-principles approaches to identify that the cobalt pnictides of CoX (X = As, Sb, Bi), none of which is a layered material in bulk form. Nevertheless, all can be stabilized as monolayered systems either in freestanding form or supported on the SrTiO3(001) substrate. We further show that each of the cobalt pnictides may potentially harbor high-Tc superconductivity beyond the Cu- and Fe-based superconducting families, and the underlying mechanism is inherently tied to their isovalency nature with the FeSe monolayer. Most strikingly, each of the monolayered CoX's on SrTiO3 is shown to be topologically nontrivial, and our findings provide promising new platforms for realizing topological superconductors in the two-dimensional limit.
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Affiliation(s)
- Jiaqing Gao
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wenjun Ding
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shunhong Zhang
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhenyu Zhang
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ping Cui
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at Microscale (HFNL), and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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50
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Zhang Y, Devakul T, Fu L. Spin-textured Chern bands in AB-stacked transition metal dichalcogenide bilayers. Proc Natl Acad Sci U S A 2021; 118:e2112673118. [PMID: 34475221 PMCID: PMC8433558 DOI: 10.1073/pnas.2112673118] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 07/29/2021] [Indexed: 11/18/2022] Open
Abstract
While transition-metal dichalcogenide (TMD)-based moiré materials have been shown to host various correlated electronic phenomena, topological states have not been experimentally observed until now [T. Li et al., Quantum anomalous Hall effect from intertwined moiré bands. arXiv [Preprint] (2021). https://arxiv.org/abs/2107.01796 (Accessed 5 July 2021)]. In this work, using first-principle calculations and continuum modeling, we reveal the displacement field-induced topological moiré bands in AB-stacked TMD heterobilayer [Formula: see text]/[Formula: see text] Valley-contrasting Chern bands with nontrivial spin texture are formed from interlayer hybridization between [Formula: see text] and [Formula: see text] bands of nominally opposite spins. Our study establishes a recipe for creating topological bands in AB-stacked TMD bilayers in general, which provides a highly tunable platform for realizing quantum-spin Hall and interaction-induced quantum anomalous Hall effects.
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Affiliation(s)
- Yang Zhang
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Trithep Devakul
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
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