1
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Hesp NCH, Batlle-Porro S, Krishna Kumar R, Agarwal H, Barcons Ruiz D, Herzig Sheinfux H, Watanabe K, Taniguchi T, Stepanov P, Koppens FHL. Cryogenic nano-imaging of second-order moiré superlattices. NATURE MATERIALS 2024:10.1038/s41563-024-01993-y. [PMID: 39256621 DOI: 10.1038/s41563-024-01993-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/03/2024] [Indexed: 09/12/2024]
Abstract
Second-order superlattices form when moiré superlattices with similar periodicities interfere with each other, leading to larger superlattice periodicities. These crystalline structures are engineered using two-dimensional materials such as graphene and hexagonal boron nitride, and the specific alignment plays a crucial role in facilitating correlation-driven topological phases. Signatures of second-order superlattices have been identified in magnetotransport experiments; however, real-space visualization is still lacking. Here we reveal the second-order superlattice in magic-angle twisted bilayer graphene closely aligned with hexagonal boron nitride through electronic transport measurements and cryogenic nanoscale photovoltage measurements and evidenced by long-range periodic photovoltage modulations. Our results show that even minuscule strain and twist-angle variations as small as 0.01° can lead to drastic changes in the second-order superlattice structure. Our real-space observations, therefore, serve as a 'magnifying glass' for strain and twist angle and can elucidate the mechanisms responsible for the breaking of spatial symmetries in twisted bilayer graphene.
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Affiliation(s)
- Niels C H Hesp
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Sergi Batlle-Porro
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Roshan Krishna Kumar
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Hitesh Agarwal
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - David Barcons Ruiz
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Hanan Herzig Sheinfux
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Petr Stepanov
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain.
- Department of Physics and Astronomy, University of Notre Dame, Notre Dame, IN, USA.
- Stavropoulos Center for Complex Quantum Matter, University of Notre Dame, Notre Dame, IN, USA.
| | - Frank H L Koppens
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain.
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain.
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2
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Tong T, Chen R, Ke Y, Wang Q, Wang X, Sun Q, Chen J, Gu Z, Yu Y, Wei H, Hao Y, Fan X, Zhang Q. Giant Second Harmonic Generation in Supertwisted WS 2 Spirals Grown in Step-Edge Particle-Induced Non-Euclidean Surfaces. ACS NANO 2024; 18:21939-21947. [PMID: 39115247 DOI: 10.1021/acsnano.4c02807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
In moiré crystals resulting from the stacking of twisted two-dimensional (2D) layered materials, a subtle adjustment in the twist angle surprisingly gives rise to a wide range of correlated optical and electrical properties. Herein, we report the synthesis of supertwisted WS2 spirals and the observation of giant second harmonic generation (SHG) in these spirals. Supertwisted WS2 spirals featuring different twist angles are synthesized on a Euclidean or step-edge particle-induced non-Euclidean surface using carefully designed water-assisted chemical vapor deposition. We observed an oscillatory dependence of SHG intensity on layer number, attributed to atomically phase-matched nonlinear dipoles within layers of supertwisted spiral crystals where inversion symmetry is restored. Through an investigation into the twist angle evolution of SHG intensity, we discovered that the stacking model between layers plays a crucial role in determining the nonlinearity, and the SHG signals in supertwisted spirals exhibit enhancements by a factor of 2 to 136 when compared with the SHG of the single-layer structure. These findings provide helpful perspectives on the rational growth of 2D twisted structures and the implementation of twist angle adjustable endowing them great potential for exploring strong coupling correlation physics and applications in the field of twistronics.
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Affiliation(s)
- Tong Tong
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
- College of Physics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Ruijie Chen
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Yuxuan Ke
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
| | - Qian Wang
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Xinchao Wang
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Qinjun Sun
- College of Physics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Jie Chen
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Zhiyuan Gu
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Ying Yu
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Hongyan Wei
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Yuying Hao
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Xiaopeng Fan
- College of Electronic Information and Optical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Qing Zhang
- School of Materials Science and Engineering, Peking University, Beijing 100871, China
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3
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Bhowmik S, Ghosh A, Chandni U. Emergent phases in graphene flat bands. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:096401. [PMID: 39059412 DOI: 10.1088/1361-6633/ad67ed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 07/26/2024] [Indexed: 07/28/2024]
Abstract
Electronic correlations in two-dimensional materials play a crucial role in stabilising emergent phases of matter. The realisation of correlation-driven phenomena in graphene has remained a longstanding goal, primarily due to the absence of strong electron-electron interactions within its low-energy bands. In this context, magic-angle twisted bilayer graphene has recently emerged as a novel platform featuring correlated phases favoured by the low-energy flat bands of the underlying moiré superlattice. Notably, the observation of correlated insulators and superconductivity, and the interplay between these phases have garnered significant attention. A wealth of correlated phases with unprecedented tunability was discovered subsequently, including orbital ferromagnetism, Chern insulators, strange metallicity, density waves, and nematicity. However, a comprehensive understanding of these closely competing phases remains elusive. The ability to controllably twist and stack multiple graphene layers has enabled the creation of a whole new family of moiré superlattices with myriad properties. Here, we review the progress and development achieved so far, encompassing the rich phase diagrams offered by these graphene-based moiré systems. Additionally, we discuss multiple phases recently observed in non-moiré multilayer graphene systems. Finally, we outline future opportunities and challenges for the exploration of hidden phases in this new generation of moiré materials.
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Affiliation(s)
- Saisab Bhowmik
- Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, India
| | - Arindam Ghosh
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - U Chandni
- Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, India
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4
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Ostovan A, Milowska KZ, García-Cervera CJ. A twist for tunable electronic and thermal transport properties of nanodevices. NANOSCALE 2024; 16:7504-7514. [PMID: 38466025 DOI: 10.1039/d4nr00058g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Twisted graphene-layered materials with nonzero interlayer twist angles (θ) have recently become appealing, as they exhibit a range of attractive physical properties, which include a Mott insulating phase and superconductivity. In this study, we consider nanodevices constructed from zigzag graphene nanoribbons with a top rectangular benzenoid [6,3]-flake. Using density functional theory and a non-equilibrium Green's function approach, we explore how the electronic and thermal transport properties in such nanodevices can be tuned through a twist of the top flake by an angle 0° ≤ θ ≤ 8.8° for different stacking configurations. We found a strong dependency of the electronic structure on the stacking type, as well as on the twisting regime, specifically in AA-stacking devices. Electron and hole van Hove singularities (vHSs), which originate, respectively, from the flatness of the top of the valence band for the minor-spin component and the bottom of the conduction band for the major-spin component, are found very close to the Fermi level in the density of states and electronic transmission spectra of AA-stacking devices with a twist angle of 1.1°. We establish that these vHSs in AA-1.1° devices are stable at higher temperatures and, with the increased number of available states, lead to larger values of electron thermal conductivity and finally total thermal conductivity in AA-1.1°. Our work highlights the essential role of twisting and stacking for the fabrication of nanoscale charge and heat switches and spurs future studies of twisted layered structures.
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Affiliation(s)
- Azar Ostovan
- Mathematics Department, University of California, Santa Barbara, CA 93106, USA.
| | - Karolina Z Milowska
- CIC nanoGUNE, Tolosa Hiribidea 76, 20018 Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | - Carlos J García-Cervera
- Mathematics Department, University of California, Santa Barbara, CA 93106, USA.
- BCAM, Basque Center for Applied Mathematics, E48009 Bilbao, Basque Country, Spain
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5
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Barrier J, Kim M, Kumar RK, Xin N, Kumaravadivel P, Hague L, Nguyen E, Berdyugin AI, Moulsdale C, Enaldiev VV, Prance JR, Koppens FHL, Gorbachev RV, Watanabe K, Taniguchi T, Glazman LI, Grigorieva IV, Fal'ko VI, Geim AK. One-dimensional proximity superconductivity in the quantum Hall regime. Nature 2024; 628:741-745. [PMID: 38658686 DOI: 10.1038/s41586-024-07271-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 03/05/2024] [Indexed: 04/26/2024]
Abstract
Extensive efforts have been undertaken to combine superconductivity and the quantum Hall effect so that Cooper-pair transport between superconducting electrodes in Josephson junctions is mediated by one-dimensional edge states1-6. This interest has been motivated by prospects of finding new physics, including topologically protected quasiparticles7-9, but also extends into metrology and device applications10-13. So far it has proven challenging to achieve detectable supercurrents through quantum Hall conductors2,3,6. Here we show that domain walls in minimally twisted bilayer graphene14-18 support exceptionally robust proximity superconductivity in the quantum Hall regime, allowing Josephson junctions to operate in fields close to the upper critical field of superconducting electrodes. The critical current is found to be non-oscillatory and practically unchanging over the entire range of quantizing fields, with its value being limited by the quantum conductance of ballistic, strictly one-dimensional, electronic channels residing within the domain walls. The system described is unique in its ability to support Andreev bound states at quantizing fields and offers many interesting directions for further exploration.
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Affiliation(s)
- Julien Barrier
- Department of Physics and Astronomy, University of Manchester, Manchester, UK.
- National Graphene Institute, University of Manchester, Manchester, UK.
| | - Minsoo Kim
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- Department of Applied Physics, Kyung Hee University, Yong-in, South Korea
| | - Roshan Krishna Kumar
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
| | - Na Xin
- Department of Physics and Astronomy, University of Manchester, Manchester, UK.
- Department of Chemistry, Zhejiang University, Hangzhou, China.
| | - P Kumaravadivel
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - Lee Hague
- National Graphene Institute, University of Manchester, Manchester, UK
| | - E Nguyen
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - A I Berdyugin
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - Christian Moulsdale
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - V V Enaldiev
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - J R Prance
- Department of Physics, Lancaster University, Lancaster, UK
| | - F H L Koppens
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain
| | - R V Gorbachev
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - K Watanabe
- National Institute for Materials Science, Tsukuba, Japan
| | - T Taniguchi
- National Institute for Materials Science, Tsukuba, Japan
| | - L I Glazman
- Department of Physics, Yale University, New Haven, CT, USA
| | - I V Grigorieva
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
| | - V I Fal'ko
- Department of Physics and Astronomy, University of Manchester, Manchester, UK
- National Graphene Institute, University of Manchester, Manchester, UK
- Henry Royce Institute for Advanced Materials, University of Manchester, Manchester, UK
| | - A K Geim
- Department of Physics and Astronomy, University of Manchester, Manchester, UK.
- National Graphene Institute, University of Manchester, Manchester, UK.
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6
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Völkl T, Aharon-Steinberg A, Holder T, Alpern E, Banu N, Pariari AK, Myasoedov Y, Huber ME, Hücker M, Zeldov E. Demonstration and imaging of cryogenic magneto-thermoelectric cooling in a van der Waals semimetal. NATURE PHYSICS 2024; 20:976-983. [PMID: 38882521 PMCID: PMC11178502 DOI: 10.1038/s41567-024-02417-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 01/25/2024] [Indexed: 06/18/2024]
Abstract
Attaining viable thermoelectric cooling at cryogenic temperatures is of considerable fundamental and technological interest for electronics and quantum materials applications. In-device temperature control can provide more efficient and precise thermal environment management compared with conventional global cooling. The application of a current and perpendicular magnetic field gives rise to cooling by generating electron-hole pairs on one side of the sample and to heating due to their recombination on the opposite side, which is known as the Ettingshausen effect. Here we develop nanoscale cryogenic imaging of the magneto-thermoelectric effect and demonstrate absolute cooling and an Ettingshausen effect in exfoliated WTe2 Weyl semimetal flakes at liquid He temperatures. In contrast to bulk materials, the cooling is non-monotonic with respect to the magnetic field and device size. Our model of magneto-thermoelectricity in mesoscopic semimetal devices shows that the cooling efficiency and the induced temperature profiles are governed by the interplay between sample geometry, electron-hole recombination length, magnetic field, and flake and substrate heat conductivities. The observations open the way for the direct integration of microscopic thermoelectric cooling and for temperature landscape engineering in van der Waals devices.
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Affiliation(s)
- T Völkl
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - A Aharon-Steinberg
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - T Holder
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel
| | - E Alpern
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - N Banu
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - A K Pariari
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Y Myasoedov
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - M E Huber
- Departments of Physics and Electrical Engineering, University of Colorado Denver, Denver, CO USA
| | - M Hücker
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
| | - E Zeldov
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel
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7
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Sun X, Suriyage M, Khan AR, Gao M, Zhao J, Liu B, Hasan MM, Rahman S, Chen RS, Lam PK, Lu Y. Twisted van der Waals Quantum Materials: Fundamentals, Tunability, and Applications. Chem Rev 2024; 124:1992-2079. [PMID: 38335114 DOI: 10.1021/acs.chemrev.3c00627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
Twisted van der Waals (vdW) quantum materials have emerged as a rapidly developing field of two-dimensional (2D) semiconductors. These materials establish a new central research area and provide a promising platform for studying quantum phenomena and investigating the engineering of novel optoelectronic properties such as single photon emission, nonlinear optical response, magnon physics, and topological superconductivity. These captivating electronic and optical properties result from, and can be tailored by, the interlayer coupling using moiré patterns formed by vertically stacking atomic layers with controlled angle misorientation or lattice mismatch. Their outstanding properties and the high degree of tunability position them as compelling building blocks for both compact quantum-enabled devices and classical optoelectronics. This paper offers a comprehensive review of recent advancements in the understanding and manipulation of twisted van der Waals structures and presents a survey of the state-of-the-art research on moiré superlattices, encompassing interdisciplinary interests. It delves into fundamental theories, synthesis and fabrication, and visualization techniques, and the wide range of novel physical phenomena exhibited by these structures, with a focus on their potential for practical device integration in applications ranging from quantum information to biosensors, and including classical optoelectronics such as modulators, light emitting diodes, lasers, and photodetectors. It highlights the unique ability of moiré superlattices to connect multiple disciplines, covering chemistry, electronics, optics, photonics, magnetism, topological and quantum physics. This comprehensive review provides a valuable resource for researchers interested in moiré superlattices, shedding light on their fundamental characteristics and their potential for transformative applications in various fields.
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Affiliation(s)
- Xueqian Sun
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Manuka Suriyage
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Ahmed Raza Khan
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Department of Industrial and Manufacturing Engineering, University of Engineering and Technology (Rachna College Campus), Gujranwala, Lahore 54700, Pakistan
| | - Mingyuan Gao
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- College of Engineering and Technology, Southwest University, Chongqing 400716, China
| | - Jie Zhao
- Department of Quantum Science & Technology, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Boqing Liu
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Md Mehedi Hasan
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Sharidya Rahman
- Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800, Australia
- ARC Centre of Excellence in Exciton Science, Monash University, Clayton, Victoria 3800, Australia
| | - Ruo-Si Chen
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Ping Koy Lam
- Department of Quantum Science & Technology, Research School of Physics, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Yuerui Lu
- School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
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8
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Zhang S, Liu Y, Sun Z, Chen X, Li B, Moore SL, Liu S, Wang Z, Rossi SE, Jing R, Fonseca J, Yang B, Shao Y, Huang CY, Handa T, Xiong L, Fu M, Pan TC, Halbertal D, Xu X, Zheng W, Schuck PJ, Pasupathy AN, Dean CR, Zhu X, Cobden DH, Xu X, Liu M, Fogler MM, Hone JC, Basov DN. Visualizing moiré ferroelectricity via plasmons and nano-photocurrent in graphene/twisted-WSe 2 structures. Nat Commun 2023; 14:6200. [PMID: 37794007 PMCID: PMC10550968 DOI: 10.1038/s41467-023-41773-x] [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: 04/12/2023] [Accepted: 09/15/2023] [Indexed: 10/06/2023] Open
Abstract
Ferroelectricity, a spontaneous and reversible electric polarization, is found in certain classes of van der Waals (vdW) materials. The discovery of ferroelectricity in twisted vdW layers provides new opportunities to engineer spatially dependent electric and optical properties associated with the configuration of moiré superlattice domains and the network of domain walls. Here, we employ near-field infrared nano-imaging and nano-photocurrent measurements to study ferroelectricity in minimally twisted WSe2. The ferroelectric domains are visualized through the imaging of the plasmonic response in a graphene monolayer adjacent to the moiré WSe2 bilayers. Specifically, we find that the ferroelectric polarization in moiré domains is imprinted on the plasmonic response of the graphene. Complementary nano-photocurrent measurements demonstrate that the optoelectronic properties of graphene are also modulated by the proximal ferroelectric domains. Our approach represents an alternative strategy for studying moiré ferroelectricity at native length scales and opens promising prospects for (opto)electronic devices.
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Affiliation(s)
- Shuai Zhang
- Department of Physics, Columbia University, New York, NY, 10027, USA.
| | - Yang Liu
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Zhiyuan Sun
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, P.R. China
| | - Xinzhong Chen
- Department of Physics, Columbia University, New York, NY, 10027, USA
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Baichang Li
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - S L Moore
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Song Liu
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Zhiying Wang
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - S E Rossi
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Ran Jing
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Jordan Fonseca
- Department of Physics, University of Washington, Seattle, WA, 98195, USA
| | - Birui Yang
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Yinming Shao
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Chun-Ying Huang
- Department of Chemistry, Columbia University, New York, NY, 10027, USA
| | - Taketo Handa
- Department of Chemistry, Columbia University, New York, NY, 10027, USA
| | - Lin Xiong
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Matthew Fu
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Tsai-Chun Pan
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Dorri Halbertal
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Xinyi Xu
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Wenjun Zheng
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - P J Schuck
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - A N Pasupathy
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - C R Dean
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Xiaoyang Zhu
- Department of Chemistry, Columbia University, New York, NY, 10027, USA
| | - David H Cobden
- Department of Physics, University of Washington, Seattle, WA, 98195, USA
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, WA, 98195, USA
| | - Mengkun Liu
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - M M Fogler
- Department of Physics, University of California, San Diego, La Jolla, CA, 92093, USA
| | - James C Hone
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, 10027, USA.
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9
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Duan J, Álvarez-Pérez G, Lanza C, Voronin K, Tresguerres-Mata AIF, Capote-Robayna N, Álvarez-Cuervo J, Tarazaga Martín-Luengo A, Martín-Sánchez J, Volkov VS, Nikitin AY, Alonso-González P. Multiple and spectrally robust photonic magic angles in reconfigurable α-MoO 3 trilayers. NATURE MATERIALS 2023:10.1038/s41563-023-01582-5. [PMID: 37349399 DOI: 10.1038/s41563-023-01582-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 05/16/2023] [Indexed: 06/24/2023]
Abstract
The emergence of a topological transition of the polaritonic dispersion in twisted bilayers of anisotropic van der Waals materials at a given twist angle-the photonic magic angle-results in the diffractionless propagation of polaritons with deep-subwavelength resolution. This type of propagation, generally referred to as canalization, holds promise for the control of light at the nanoscale. However, the existence of a single photonic magic angle hinders such control since the canalization direction in twisted bilayers is unique and fixed for each incident frequency. Here we overcome this limitation by demonstrating multiple spectrally robust photonic magic angles in reconfigurable twisted α-phase molybdenum trioxide (α-MoO3) trilayers. We show that canalization of polaritons can be programmed at will along any desired in-plane direction in a single device with broad spectral ranges. These findings open the door for nanophotonics applications where on-demand control is crucial, such as thermal management, nanoimaging or entanglement of quantum emitters.
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Affiliation(s)
- J Duan
- Department of Physics, University of Oviedo, Oviedo, Spain.
- Center of Research on Nanomaterials and Nanotechnology, CINN (CSIC-Universidad de Oviedo), El Entrego, Spain.
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, China.
- Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing, China.
| | - G Álvarez-Pérez
- Department of Physics, University of Oviedo, Oviedo, Spain
- Center of Research on Nanomaterials and Nanotechnology, CINN (CSIC-Universidad de Oviedo), El Entrego, Spain
| | - C Lanza
- Department of Physics, University of Oviedo, Oviedo, Spain
| | - K Voronin
- Donostia International Physics Center (DIPC), Donostia, San Sebastián, Spain
| | | | - N Capote-Robayna
- Donostia International Physics Center (DIPC), Donostia, San Sebastián, Spain
| | | | | | - J Martín-Sánchez
- Department of Physics, University of Oviedo, Oviedo, Spain
- Center of Research on Nanomaterials and Nanotechnology, CINN (CSIC-Universidad de Oviedo), El Entrego, Spain
| | - V S Volkov
- XPANCEO, Bayan Business Center, DIP, Dubai, UAE
| | - A Y Nikitin
- Donostia International Physics Center (DIPC), Donostia, San Sebastián, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
| | - P Alonso-González
- Department of Physics, University of Oviedo, Oviedo, Spain.
- Center of Research on Nanomaterials and Nanotechnology, CINN (CSIC-Universidad de Oviedo), El Entrego, Spain.
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10
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Guo X, Lyu W, Chen T, Luo Y, Wu C, Yang B, Sun Z, García de Abajo FJ, Yang X, Dai Q. Polaritons in Van der Waals Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2201856. [PMID: 36121344 DOI: 10.1002/adma.202201856] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 08/15/2022] [Indexed: 05/17/2023]
Abstract
2D monolayers supporting a wide variety of highly confined plasmons, phonon polaritons, and exciton polaritons can be vertically stacked in van der Waals heterostructures (vdWHs) with controlled constituent layers, stacking sequence, and even twist angles. vdWHs combine advantages of 2D material polaritons, rich optical structure design, and atomic scale integration, which have greatly extended the performance and functions of polaritons, such as wide frequency range, long lifetime, ultrafast all-optical modulation, and photonic crystals for nanoscale light. Here, the state of the art of 2D material polaritons in vdWHs from the perspective of design principles and potential applications is reviewed. Some fundamental properties of polaritons in vdWHs are initially discussed, followed by recent discoveries of plasmons, phonon polaritons, exciton polaritons, and their hybrid modes in vdWHs. The review concludes with a perspective discussion on potential applications of these polaritons such as nanophotonic integrated circuits, which will benefit from the intersection between nanophotonics and materials science.
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Affiliation(s)
- Xiangdong Guo
- 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, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Wei Lyu
- 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, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Tinghan 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, 100190, P. R. China
- School of Life Science, Peking University, Beijing, 100871, P. R. China
| | - Yang Luo
- 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, 100190, P. R. China
- School of Life Science, Peking University, Beijing, 100871, P. R. China
| | - Chenchen Wu
- 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, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Bei Yang
- 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, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Zhipei Sun
- Department of Electronics and Nanoengineering and QTF Centre of Excellence, Department of Applied Physics, Aalto University, Espoo, 02150, Finland
| | - F Javier García de Abajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, 08860, Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, Barcelona, 08010, Spain
| | - Xiaoxia Yang
- 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, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - 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, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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11
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Siday T, Sandner F, Brem S, Zizlsperger M, Perea-Causin R, Schiegl F, Nerreter S, Plankl M, Merkl P, Mooshammer F, Huber MA, Malic E, Huber R. Ultrafast Nanoscopy of High-Density Exciton Phases in WSe 2. NANO LETTERS 2022; 22:2561-2568. [PMID: 35157466 DOI: 10.1021/acs.nanolett.1c04741] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The density-driven transition of an exciton gas into an electron-hole plasma remains a compelling question in condensed matter physics. In two-dimensional transition metal dichalcogenides, strongly bound excitons can undergo this phase change after transient injection of electron-hole pairs. Unfortunately, unavoidable nanoscale inhomogeneity in these materials has impeded quantitative investigation into this elusive transition. Here, we demonstrate how ultrafast polarization nanoscopy can capture the Mott transition through the density-dependent recombination dynamics of electron-hole pairs within a WSe2 homobilayer. For increasing carrier density, an initial monomolecular recombination of optically dark excitons transitions continuously into a bimolecular recombination of an unbound electron-hole plasma above 7 × 1012 cm-2. We resolve how the Mott transition modulates over nanometer length scales, directly evidencing the strong inhomogeneity in stacked monolayers. Our results demonstrate how ultrafast polarization nanoscopy could unveil the interplay of strong electronic correlations and interlayer coupling within a diverse range of stacked and twisted two-dimensional materials.
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Affiliation(s)
- Thomas Siday
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Fabian Sandner
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Samuel Brem
- Department of Physics, Philipps-Universität Marburg, 35032 Marburg, Germany
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Martin Zizlsperger
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Raul Perea-Causin
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Felix Schiegl
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Svenja Nerreter
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Markus Plankl
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Philipp Merkl
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Fabian Mooshammer
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Markus A Huber
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
| | - Ermin Malic
- Department of Physics, Philipps-Universität Marburg, 35032 Marburg, Germany
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Rupert Huber
- Department of Physics and Regensburg Center for Ultrafast Nanoscopy (RUN), University of Regensburg, 93040 Regensburg, Germany
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12
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Tang L, Zhang A, Zhang Z, Zhao Q, Li J, Mei Y, Yin Y, Wang W. Multifunctional inorganic nanomaterials for cancer photoimmunotherapy. Cancer Commun (Lond) 2022; 42:141-163. [PMID: 35001556 PMCID: PMC8822595 DOI: 10.1002/cac2.12255] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 09/24/2021] [Accepted: 12/30/2021] [Indexed: 12/12/2022] Open
Abstract
Phototherapy and immunotherapy in combination is regarded as the ideal therapeutic modality to treat both primary and metastatic tumors. Immunotherapy uses different immunological approaches to stimulate the immune system to identify tumor cells for targeted elimination. Phototherapy destroys the primary tumors by light irradiation, which induces a series of immune responses through triggering immunogenic cancer cell death. Therefore, when integrating immunotherapy with phototherapy, a novel anti-cancer strategy called photoimmunotherapy (PIT) is emerging. This synergistic treatment modality can not only enhance the effectiveness of both therapies but also overcome their inherent limitations, opening a new era for the current anti-cancer therapy. Recently, the advancement of nanomaterials affords a platform for PIT. From all these nanomaterials, inorganic nanomaterials stand out as ideal mediators in PIT due to their unique physiochemical properties. Inorganic nanomaterials can not only serve as carriers to transport immunomodulatory agents in immunotherapy owing to their excellent drug-loading capacity but also function as photothermal agents or photosensitizers in phototherapy because of their great optical characteristics. In this review, the recent advances of multifunctional inorganic nanomaterial-mediated drug delivery and their contributions to cancer PIT will be highlighted.
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Affiliation(s)
- Lu Tang
- State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China.,National Medical Products Administration Key Laboratory for Research and Evaluation of Pharmaceutical Preparations and Excipients, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China
| | - Aining Zhang
- State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China.,National Medical Products Administration Key Laboratory for Research and Evaluation of Pharmaceutical Preparations and Excipients, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China
| | - Ziyao Zhang
- State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China.,National Medical Products Administration Key Laboratory for Research and Evaluation of Pharmaceutical Preparations and Excipients, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China
| | - Qingqing Zhao
- State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China.,National Medical Products Administration Key Laboratory for Research and Evaluation of Pharmaceutical Preparations and Excipients, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China
| | - Jing Li
- State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China.,National Medical Products Administration Key Laboratory for Research and Evaluation of Pharmaceutical Preparations and Excipients, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China
| | - Yijun Mei
- State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China.,National Medical Products Administration Key Laboratory for Research and Evaluation of Pharmaceutical Preparations and Excipients, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China
| | - Yue Yin
- State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China.,National Medical Products Administration Key Laboratory for Research and Evaluation of Pharmaceutical Preparations and Excipients, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China
| | - Wei Wang
- State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China.,National Medical Products Administration Key Laboratory for Research and Evaluation of Pharmaceutical Preparations and Excipients, China Pharmaceutical University, Nanjing, Jiangsu, P. R. China
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13
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Nonlinear nanoelectrodynamics of a Weyl metal. Proc Natl Acad Sci U S A 2021; 118:2116366118. [PMID: 34819380 DOI: 10.1073/pnas.2116366118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/25/2021] [Indexed: 11/18/2022] Open
Abstract
Chiral Weyl fermions with linear energy-momentum dispersion in the bulk accompanied by Fermi-arc states on the surfaces prompt a host of enticing optical effects. While new Weyl semimetal materials keep emerging, the available optical probes are limited. In particular, isolating bulk and surface electrodynamics in Weyl conductors remains a challenge. We devised an approach to the problem based on near-field photocurrent imaging at the nanoscale and applied this technique to a prototypical Weyl semimetal TaIrTe4 As a first step, we visualized nano-photocurrent patterns in real space and demonstrated their connection to bulk nonlinear conductivity tensors through extensive modeling augmented with density functional theory calculations. Notably, our nanoscale probe gives access to not only the in-plane but also the out-of-plane electric fields so that it is feasible to interrogate all allowed nonlinear tensors including those that remained dormant in conventional far-field optics. Surface- and bulk-related nonlinear contributions are distinguished through their "symmetry fingerprints" in the photocurrent maps. Robust photocurrents also appear at mirror-symmetry breaking edges of TaIrTe4 single crystals that we assign to nonlinear conductivity tensors forbidden in the bulk. Nano-photocurrent spectroscopy at the boundary reveals a strong resonance structure absent in the interior of the sample, providing evidence for elusive surface states.
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14
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Chan MC, Chen YC, Shiue BH, Tsai TI, Chen CD, Tseng WS. Correlation between the optical absorption and twisted angle of bilayer graphene observed by high-resolution reflectance confocal laser microscopy. OPTICS EXPRESS 2021; 29:40481-40493. [PMID: 34809387 DOI: 10.1364/oe.431305] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 11/04/2021] [Indexed: 06/13/2023]
Abstract
We report a systematic study of the optical absorption of twisted bilayer graphene (tBLG) across a large range of twist angles from 0° to 30° using a high-resolution reflectance confocal laser microscopy (RCLM) system. The high-quality single crystalline tBLG was synthesized via the efficient plasma enhanced chemical vapor deposition techniques without the need of active heating. The sensitivity of acquired images from the RCLM were better than conventional optical microscopes. Although the highest spatial resolution of RCLM is still lower than scanning electron microscopes, it possesses the advantages of beam-damage and vacuum free. Moreover, the high intensity-resolution (sensitivity) images firstly allowed us to distinguish the slight absorption differences and analyze the correlation between the optical absorption and twisted angle of tBLG after data processing procedures. A maximum absorption (minimum transmission) was observed at the stacking angle of tBLG from 10° to 20°, indicating the interplay between the laser and the electron/hole van-Hove singularities when tBLG oriented around the critical angle (θc∼13°). The twisted angle correlated optical absorption paves an alternative way not only to visibly identify the interlayer orientation of tBLG but also to reflect the characterization of the interlayer coupling via its band structure.
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15
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Chen X, Yao Z, Stanciu SG, Basov DN, Hillenbrand R, Liu M. Rapid simulations of hyperspectral near-field images of three-dimensional heterogeneous surfaces. OPTICS EXPRESS 2021; 29:39648-39668. [PMID: 34809324 DOI: 10.1364/oe.440821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/12/2021] [Indexed: 05/27/2023]
Abstract
The scattering-type scanning near-field optical microscope (s-SNOM) has emerged as a powerful tool for resolving nanoscale inhomogeneities in laterally heterogeneous samples. However, most analytical models used to predict the scattering near-field signals are assuming homogenous landscapes (bulk materials), resulting in inconsistencies when applied to samples with more complex configurations. In this work, we combine the point-dipole model (PDM) to the finite-element method (FEM) to account for the lateral and vertical heterogeneities while keeping the computation time manageable. Full images, spectra, or hyperspectral line profiles can be simulated by calculating the self-consistent dipole radiation demodulated at higher harmonics of the tip oscillation, mimicking real experimental procedures. Using this formalism, we clarify several important yet puzzling experimental observations in near-field images on samples with rich typography and complex material compositions, heterostructures of two-dimensional material flakes, and plasmonic antennas. The developed method serves as a basis for future investigations of nano-systems with nontrivial topography.
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16
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Malard LM, Lafeta L, Cunha RS, Nadas R, Gadelha A, Cançado LG, Jorio A. Studying 2D materials with advanced Raman spectroscopy: CARS, SRS and TERS. Phys Chem Chem Phys 2021; 23:23428-23444. [PMID: 34651627 DOI: 10.1039/d1cp03240b] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Raman spectroscopy has been established as a valuable tool to study and characterize two-dimensional (2D) systems, but it exhibits two drawbacks: a relatively weak signal response and a limited spatial resolution. Recently, advanced Raman spectroscopy techniques, such as coherent anti-Stokes spectroscopy (CARS), stimulated Raman scattering (SRS) and tip-enhanced Raman spectroscopy (TERS), have been shown to overcome these two limitations. In this article, we review how useful physical information can be retrieved from different 2D materials using these three advanced Raman spectroscopy and imaging techniques, discussing results on graphene, hexagonal boron-nitride, and transition metal di- and mono-chalcogenides, thus providing perspectives for future work in this early-stage field of research, including similar studies on unexplored 2D systems and open questions.
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Affiliation(s)
- Leandro M Malard
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
| | - Lucas Lafeta
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
| | - Renan S Cunha
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
| | - Rafael Nadas
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
| | - Andreij Gadelha
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
| | - Luiz Gustavo Cançado
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
| | - Ado Jorio
- Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
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17
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Nikitin AY. Photothermal twistronics. NATURE NANOTECHNOLOGY 2021; 16:489-490. [PMID: 33782591 DOI: 10.1038/s41565-021-00890-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
- Alexey Y Nikitin
- Donostia International Physics Center, Donostia-San Sebastián, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
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18
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Sunku SS, Halbertal D, Stauber T, Chen S, McLeod AS, Rikhter A, Berkowitz ME, Lo CFB, Gonzalez-Acevedo DE, Hone JC, Dean CR, Fogler MM, Basov DN. Hyperbolic enhancement of photocurrent patterns in minimally twisted bilayer graphene. Nat Commun 2021; 12:1641. [PMID: 33712611 PMCID: PMC7955135 DOI: 10.1038/s41467-021-21792-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 02/11/2021] [Indexed: 11/18/2022] Open
Abstract
Quasi-periodic moiré patterns and their effect on electronic properties of twisted bilayer graphene have been intensely studied. At small twist angle θ, due to atomic reconstruction, the moiré superlattice morphs into a network of narrow domain walls separating micron-scale AB and BA stacking regions. We use scanning probe photocurrent imaging to resolve nanoscale variations of the Seebeck coefficient occurring at these domain walls. The observed features become enhanced in a range of mid-infrared frequencies where the hexagonal boron nitride substrate is optically hyperbolic. Our results illustrate the capabilities of the nano-photocurrent technique for probing nanoscale electronic inhomogeneities in two-dimensional materials.
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Affiliation(s)
- S S Sunku
- Department of Physics, Columbia University, New York, NY, 10027, USA
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, 10027, USA
| | - D Halbertal
- Department of Physics, Columbia University, New York, NY, 10027, USA.
| | - T Stauber
- Departamento de Teoría y Simulación de Materiales, Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, 28049, Spain
| | - S Chen
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - A S McLeod
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - A Rikhter
- Department of Physics, University of California, San Diego, La Jolla, CA, 92093, USA
| | - M E Berkowitz
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - C F B Lo
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | | | - J C Hone
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - C R Dean
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - M M Fogler
- Department of Physics, University of California, San Diego, La Jolla, CA, 92093, USA
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, 10027, USA
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