1
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Long M, Jimeno-Pozo A, Sainz-Cruz H, Pantaleón PA, Guinea F. Evolution of superconductivity in twisted graphene multilayers. Proc Natl Acad Sci U S A 2024; 121:e2405259121. [PMID: 39078673 DOI: 10.1073/pnas.2405259121] [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: 03/13/2024] [Accepted: 06/25/2024] [Indexed: 07/31/2024] Open
Abstract
The group of moiré graphene superconductors keeps growing, and by now it contains twisted graphene multilayers as well as untwisted stacks. We analyze here the contribution of long-range charge fluctuations in the superconductivity of twisted double bilayers and helical trilayers, and compare the results to twisted bilayer graphene. A diagrammatic approach which depends on a few, well-known parameters is used. We find that the critical temperature and the order parameter differ significantly between twisted double bilayers and helical trilayers on one hand, and twisted bilayer graphene on the other. This trend, consistent with experiments, can be associated with the role played by moiré Umklapp processes in the different systems.
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Affiliation(s)
- Min Long
- Instituto Madrileño de Estudios Avanzados en Nanociencia, Madrid 28049, Spain
- Department of Physics, The University of Hong Kong - University of Chinese Academy of Science Joint Institute of Theoretical and Computational Physics, Hong Kong Administrative Region 999077, China
| | | | - Héctor Sainz-Cruz
- Instituto Madrileño de Estudios Avanzados en Nanociencia, Madrid 28049, Spain
| | - Pierre A Pantaleón
- Instituto Madrileño de Estudios Avanzados en Nanociencia, Madrid 28049, Spain
| | - Francisco Guinea
- Instituto Madrileño de Estudios Avanzados en Nanociencia, Madrid 28049, Spain
- Donostia International Physics Center, San Sebastián 20018, Spain
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2
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Lu YY, Mu ZN, Huang Y, Guo GR, Li HH, Xiong SJ, Zhong JX. Effects of edge disorder on the stability of quantum oscillations in two-dimensional coupled systems. Sci Rep 2024; 14:15528. [PMID: 38969744 PMCID: PMC11226721 DOI: 10.1038/s41598-024-66391-5] [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: 04/25/2024] [Accepted: 07/01/2024] [Indexed: 07/07/2024] Open
Abstract
This paper utilizes the theory of quantum diffusion to analyze the electron probability and spreading width of a wavepacket on each layer in a two-dimensional (2D) coupled system with edge disorder, aiming to clarify the effects of edge disorder on the stability of the electron periodic oscillations in 2D coupled systems. Using coupled 2D square lattices with edge disorder as an example, we show that, the electron probability and wavepacket spreading width exhibit periodic oscillations and damped oscillations, respectively, before and after the wavepacket reaches the boundary. Furthermore, these electron oscillations exhibit strong resistance against disorder perturbation with a longer decay time in the regime of large disorder, due to the combined influences of ordered and disordered site energies in the central and edge regions. Finally, we numerically verified the universality of the results through bilayer graphene, demonstrating that this anomalous quantum oscillatory behavior is independent of lattice geometry. Our findings are helpful in designing relevant quantum devices and understanding the influence of edge disorder on the stability of electron periodic oscillations in 2D coupled systems.
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Affiliation(s)
- Yan-Yan Lu
- School of Computer and Information Engineering, Guizhou University of Commerce, Guizhou, 550014, China.
| | - Zhao-Nan Mu
- School of Computer and Information Engineering, Guizhou University of Commerce, Guizhou, 550014, China
| | - Yu Huang
- Guizhou Power Grid Company Limited Guiyang Power Supply Bureau, Guizhou, 550001, China
| | - Gui-Rong Guo
- School of Computer and Information Engineering, Guizhou University of Commerce, Guizhou, 550014, China
| | - Han-Hui Li
- School of Computer and Information Engineering, Guizhou University of Commerce, Guizhou, 550014, China
| | - Shao-Jie Xiong
- School of Computer and Information Engineering, Guizhou University of Commerce, Guizhou, 550014, China
| | - Jian-Xin Zhong
- Institute for Quantum Science and Technology, Shanghai University, Shanghai, 200444, China
- School of Physics and Optoelectronics, Xiangtan University, Hunan, 411105, China
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3
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Li C, Xu F, Li B, Li J, Li G, Watanabe K, Taniguchi T, Tong B, Shen J, Lu L, Jia J, Wu F, Liu X, Li T. Tunable superconductivity in electron- and hole-doped Bernal bilayer graphene. Nature 2024; 631:300-306. [PMID: 38898282 DOI: 10.1038/s41586-024-07584-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: 12/15/2023] [Accepted: 05/17/2024] [Indexed: 06/21/2024]
Abstract
Graphene-based, high-quality, two-dimensional electronic systems have emerged as a highly tunable platform for studying superconductivity1-21. Specifically, superconductivity has been observed in both electron- and hole-doped twisted graphene moiré systems1-17, whereas in crystalline graphene systems, superconductivity has so far been observed only in hole-doped rhombohedral trilayer graphene (RTG)18 and hole-doped Bernal bilayer graphene (BBG)19-21. Recently, enhanced superconductivity has been demonstrated20,21 in BBG because of the proximity to a monolayer WSe2. Here we report the observation of superconductivity and a series of flavour-symmetry-breaking phases in electron- and hole-doped BBG/WSe2 devices by electrostatic doping. The strength of the observed superconductivity is tunable by applied vertical electric fields. The maximum Berezinskii-Kosterlitz-Thouless transition temperature for the electron- and hole-doped superconductivity is about 210 mK and 400 mK, respectively. Superconductivities emerge only when the applied electric fields drive the BBG electron or hole wavefunctions towards the WSe2 layer, underscoring the importance of the WSe2 layer in the observed superconductivity. The hole-doped superconductivity violates the Pauli paramagnetic limit, consistent with an Ising-like superconductor. By contrast, the electron-doped superconductivity obeys the Pauli limit, although the proximity-induced Ising spin-orbit coupling is also notable in the conduction band. Our findings highlight the rich physics associated with the conduction band in BBG, paving the way for further studies into the superconducting mechanisms of crystalline graphene and the development of superconductor devices based on BBG.
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Affiliation(s)
- Chushan Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China
| | - Fan Xu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Bohao Li
- School of Physics and Technology, Wuhan University, Wuhan, China
| | - Jiayi Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | - Guoan Li
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Kenji Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Bingbing Tong
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Jie Shen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Li Lu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, China
- Hefei National Laboratory, Hefei, China
| | - Jinfeng Jia
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China
- Hefei National Laboratory, Hefei, China
- Shanghai Research Center for Quantum Sciences, Shanghai, China
| | - Fengcheng Wu
- School of Physics and Technology, Wuhan University, Wuhan, China.
- Wuhan Institute of Quantum Technology, Wuhan, China.
| | - Xiaoxue Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China.
- Hefei National Laboratory, Hefei, China.
- Shanghai Research Center for Quantum Sciences, Shanghai, China.
| | - Tingxin Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, China.
- Hefei National Laboratory, Hefei, China.
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4
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Wang W, Zhou G, Lin W, Feng Z, Wang Y, Liang M, Zhang Z, Wu M, Liu L, Watanabe K, Taniguchi T, Yang W, Zhang G, Liu K, Gao J, Liu Y, Xie XC, Song Z, Lu X. Correlated Charge Density Wave Insulators in Chirally Twisted Triple Bilayer Graphene. PHYSICAL REVIEW LETTERS 2024; 132:246501. [PMID: 38949356 DOI: 10.1103/physrevlett.132.246501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 05/07/2024] [Indexed: 07/02/2024]
Abstract
Electrons residing in a flat-band system can play a vital role in triggering spectacular phenomenology due to relatively large interactions and spontaneous breaking of different degeneracies. In this work, we demonstrate chirally twisted triple bilayer graphene, a new moiré structure formed by three pieces of helically stacked Bernal bilayer graphene, as a highly tunable flat-band system. In addition to the correlated insulators showing at integer moiré fillings, commonly attributed to interaction induced symmetry broken isospin flavors in graphene, we observe abundant insulating states at half-integer moiré fillings, suggesting a longer-range interaction and the formation of charge density wave insulators which spontaneously break the moiré translation symmetry. With weak out-of-plane magnetic field applied, as observed half-integer filling states are enhanced and more quarter-integer filling states appear, pointing toward further quadrupling moiré unit cells. The insulating states at fractional fillings combined with Hartree-Fock calculations demonstrate the observation of a new type of correlated charge density wave insulators in graphene and points to a new accessible twist manner engineering correlated moiré electronics.
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Affiliation(s)
| | | | | | - Zuo Feng
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Centre for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China
| | | | | | | | | | | | | | | | | | | | - Kaihui Liu
- State Key Laboratory for Mesoscopic Physics, Frontiers Science Centre for Nano-optoelectronics, School of Physics, Peking University, 100871, Beijing, China
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5
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Zhao Z, Zhang T, Yue S, Wang P, Bao Y, Zhan S. Spin Polarization: A New Frontier in Efficient Photocatalysis for Environmental Purification and Energy Conversion. Chemphyschem 2024; 25:e202300726. [PMID: 38059760 DOI: 10.1002/cphc.202300726] [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: 10/03/2023] [Revised: 11/28/2023] [Accepted: 12/01/2023] [Indexed: 12/08/2023]
Abstract
As a promising strategy to improve photocatalytic efficiency, spin polarization has attracted enormous attention in recent years, which could be involved in various steps of photoreaction. The Pauli repulsion principle and the spin selection rule dictate that the behavior of two electrons in a spatial eigenstate is based on their spin states, and this fact opens up a new avenue for manipulating photocatalytic efficiency. In this review, recent advances in modulating the photocatalytic activity with spin polarization are systematically summarized. Fundamental insights into the influence of spin-polarization effects on photon absorption, carrier separation, and migration, and the behaviors of reaction-related substances from the photon uptake to reactant desorption are highlighted and discussed in detail, and various photocatalytic applications for environmental purification and energy conversion are presented. This review is expected to deliver a timely overview of the recent developments in spin-polarization-modulated photocatalysis for environmental purification and energy conversion in terms of their practical applications.
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Affiliation(s)
- Zhiyong Zhao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
| | - Tao Zhang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
| | - Shuai Yue
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
| | - Pengfei Wang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
| | - Yueping Bao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
| | - Sihui Zhan
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
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6
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Lu X, Xie B, Yang Y, Zhang Y, Kong X, Li J, Ding F, Wang ZJ, Liu J. Magic Momenta and Three-Dimensional Landau Levels from a Three-Dimensional Graphite Moiré Superlattice. PHYSICAL REVIEW LETTERS 2024; 132:056601. [PMID: 38364175 DOI: 10.1103/physrevlett.132.056601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 11/17/2023] [Accepted: 01/04/2024] [Indexed: 02/18/2024]
Abstract
In this Letter, we theoretically explore the physical properties of a new type of three-dimensional graphite moiré superlattice, the bulk alternating twisted graphite (ATG) system with homogeneous twist angle, which is grown by in situ chemical vapor decomposition method. Compared to twisted bilayer graphene (TBG), the bulk ATG system is bestowed with an additional wave vector degree of freedom due to the extra dimensionality. As a result, when the twist angle of bulk ATG is smaller than twice of the magic angle of TBG, there always exist "magic momenta" which host topological flat bands with vanishing in-plane Fermi velocities. Most saliently, when the twist angle is relatively large, a dispersionless three-dimensional zeroth Landau level would emerge in the bulk ATG, which may give rise to robust three-dimensional quantum Hall effects and unusual quantum-Hall physics over a large range of twist angles.
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Affiliation(s)
- Xin Lu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
| | - Bo Xie
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
| | - Yue Yang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yiwen Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
| | - Xiao Kong
- Institute of Technology for Carbon Neutrality, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
- Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, China
| | - Jun Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
| | - Feng Ding
- Institute of Technology for Carbon Neutrality, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
- Faculty of Materials Science and Energy Engineering, Shenzhen University of Advanced Technology, Shenzhen, China
| | - Zhu-Jun Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jianpeng Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
- Liaoning Academy of Materials, Shenyang 110167, China
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7
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Chen F, Zhang Y, Wang M, Liu J, Hai W, Liu Y. Chitosan modified graphene field-effect transistor biosensor for ultrasensitive procalcitonin detection. Talanta 2024; 268:125308. [PMID: 37862752 DOI: 10.1016/j.talanta.2023.125308] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 10/06/2023] [Accepted: 10/12/2023] [Indexed: 10/22/2023]
Abstract
Sepsis is a systemic inflammatory response caused by a bacterial infection that often leading to tissue damage, organ failure and death. Procalcitonin (PCT), as a peptide precursor to hormones, is the main biomarker to identification of the sepsis. In this study, a chitosan modified graphene field transistor (CTS-GFET) was established and first time used for PCT ultra-sensitive detection. CTS was functionalized on the GFET channel surface to immobilized anti-PCT by glutaraldehyde. This biosensor exhibited the detection limit as low as 0.82 ag/mL in PBS, which exhibited 3 times enhancement compared with GFET biosensors. The enhancement mechanisms of CTS-GFET were studied by electrical theoretical model. In addition, the CTS-GFET biosensor was successfully applied to quantify the concentration of the PCT in human serum samples, indicating the potential use in clinical application.
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Affiliation(s)
- Furong Chen
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), College Chemistry and Materials Science, Inner Mongolia Minzu University, Tongliao, 028000, People's Republic of China
| | - Ying Zhang
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), College Chemistry and Materials Science, Inner Mongolia Minzu University, Tongliao, 028000, People's Republic of China
| | - Mingxuan Wang
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), College Chemistry and Materials Science, Inner Mongolia Minzu University, Tongliao, 028000, People's Republic of China
| | - Jinghai Liu
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), College Chemistry and Materials Science, Inner Mongolia Minzu University, Tongliao, 028000, People's Republic of China
| | - Wenfeng Hai
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), College Chemistry and Materials Science, Inner Mongolia Minzu University, Tongliao, 028000, People's Republic of China.
| | - Yushuang Liu
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), College Chemistry and Materials Science, Inner Mongolia Minzu University, Tongliao, 028000, People's Republic of China; Key Laboratory of Mongolian Medicine Research and Development Engineering, Ministry of Education, Inner Mongolia Minzu University, Tongliao, 028000, People's Republic of China.
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8
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Iwakiri S, Mestre-Torà A, Portolés E, Visscher M, Perego M, Zheng G, Taniguchi T, Watanabe K, Sigrist M, Ihn T, Ensslin K. Tunable quantum interferometer for correlated moiré electrons. Nat Commun 2024; 15:390. [PMID: 38195747 PMCID: PMC10776667 DOI: 10.1038/s41467-023-44671-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 12/20/2023] [Indexed: 01/11/2024] Open
Abstract
Magic-angle twisted bilayer graphene can host a variety of gate-tunable correlated states - including superconducting and correlated insulator states. Recently, junction-based superconducting moiré devices have been introduced, enabling the study of the charge, spin and orbital nature of superconductivity, as well as the coherence of moiré electrons in magic-angle twisted bilayer graphene. Complementary fundamental coherence effects-in particular, the Little-Parks effect in a superconducting ring and the Aharonov-Bohm effect in a normally conducting ring - have not yet been reported in moiré devices. Here, we observe both phenomena in a single gate-defined ring device, where we can embed a superconducting or normally conducting ring in a correlated or band insulator. The Little-Parks effect is seen in the superconducting phase diagram as a function of density and magnetic field, confirming the effective charge of 2e. We also find that the coherence length of conducting moiré electrons exceeds several microns at 50 mK. In addition, we identify a regime characterized by h/e-periodic oscillations but with superconductor-like nonlinear transport.
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Affiliation(s)
- Shuichi Iwakiri
- Laboratory for Solid State Physics, ETH Zurich, CH-8093, Zurich, Switzerland.
| | | | - Elías Portolés
- Laboratory for Solid State Physics, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Marieke Visscher
- Laboratory for Solid State Physics, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Marta Perego
- Laboratory for Solid State Physics, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Giulia Zheng
- Laboratory for Solid State Physics, ETH Zurich, CH-8093, Zurich, Switzerland
| | - 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
| | - Manfred Sigrist
- Institute for Theoretical Physics, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Thomas Ihn
- Laboratory for Solid State Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Klaus Ensslin
- Laboratory for Solid State Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
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9
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Christos M, Sachdev S, Scheurer MS. Nodal band-off-diagonal superconductivity in twisted graphene superlattices. Nat Commun 2023; 14:7134. [PMID: 37932262 PMCID: PMC10628137 DOI: 10.1038/s41467-023-42471-4] [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: 04/14/2023] [Accepted: 10/11/2023] [Indexed: 11/08/2023] Open
Abstract
The superconducting state and mechanism are among the least understood phenomena in twisted graphene systems. Recent tunneling experiments indicate a transition between nodal and gapped pairing with electron filling, which is not naturally understood within current theory. We demonstrate that the coexistence of superconductivity and flavor polarization leads to pairing channels that are guaranteed by symmetry to be entirely band-off-diagonal, with a variety of consequences: most notably, the pairing invariant under all symmetries can have Bogoliubov Fermi surfaces in the superconducting state with protected nodal lines, or may be fully gapped, depending on parameters, and the band-off-diagonal chiral p-wave state exhibits transitions between gapped and nodal regions upon varying the doping. We demonstrate that band-off-diagonal pairing can be the leading state when only phonons are considered, and is also uniquely favored by fluctuations of a time-reversal-symmetric intervalley coherent order motivated by recent experiments. Consequently, band-off-diagonal superconductivity allows for the reconciliation of several key experimental observations in graphene moiré systems.
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Affiliation(s)
- Maine Christos
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Subir Sachdev
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Mathias S Scheurer
- Institute for Theoretical Physics, University of Innsbruck, Innsbruck, A-6020, Austria.
- Institute for Theoretical Physics III, University of Stuttgart, 70550, Stuttgart, Germany.
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10
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Su R, Kuiri M, Watanabe K, Taniguchi T, Folk J. Superconductivity in twisted double bilayer graphene stabilized by WSe 2. NATURE MATERIALS 2023; 22:1332-1337. [PMID: 37640863 DOI: 10.1038/s41563-023-01653-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 07/25/2023] [Indexed: 08/31/2023]
Abstract
Identifying the essential components of superconductivity in graphene-based systems remains a critical problem in two-dimensional materials research. This field is connected to the mysteries that underpin investigations of unconventional superconductivity in condensed-matter physics. Superconductivity has been observed in magic-angle twisted stacks of monolayer graphene but conspicuously not in twisted stacks of bilayer graphene, although both systems host topological flat bands and symmetry-broken states. Here we report the discovery of superconductivity in twisted double bilayer graphene (TDBG) in proximity to WSe2. Samples with twist angles 1.24° and 1.37° superconduct in small pockets of the gate-tuned phase diagram within the valence and conduction band, respectively. Superconductivity emerges from unpolarized phases near van Hove singularities and next to regions with broken isospin symmetry. Our results show the correlation between a high density of states and the emergence of superconductivity in TDBG while revealing a possible role for isospin fluctuations in the pairing.
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Affiliation(s)
- Ruiheng Su
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - Manabendra Kuiri
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - 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
| | - Joshua Folk
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia, Canada.
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.
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11
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Wang S, Song J, Sun M, Cao S. Emerging Characteristics and Properties of Moiré Materials. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2881. [PMID: 37947726 PMCID: PMC10649551 DOI: 10.3390/nano13212881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 10/26/2023] [Accepted: 10/29/2023] [Indexed: 11/12/2023]
Abstract
In recent years, scientists have conducted extensive research on Moiré materials and have discovered some compelling properties. The Moiré superlattice allows superconductivity through flat-band and strong correlation effects. The presence of flat bands causes the Moiré material to exhibit topological properties as well. Modulating electronic interactions with magnetic fields in Moiré materials enables the fractional quantum Hall effect. In addition, Moiré materials have ferromagnetic and antiferromagnetic properties. By tuning the interlayer coupling and spin interactions of the Moiré superlattice, different magnetic properties can be achieved. Finally, this review also discusses the applications of Moiré materials in the fields of photocurrent, superconductivity, and thermoelectricity. Overall, Moiré superlattices provide a new dimension in the development of two-dimensional materials.
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Affiliation(s)
- Shaofeng Wang
- School of Physics, Liaoning University, Shenyang 110036, China
| | - Jizhe Song
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China;
| | - Mengtao Sun
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China;
| | - Shuo Cao
- School of Physics, Liaoning University, Shenyang 110036, China
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12
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Slot MR, Maximenko Y, Haney PM, Kim S, Walkup DT, Strelcov E, Le ST, Shih EM, Yildiz D, Blankenship SR, Watanabe K, Taniguchi T, Barlas Y, Zhitenev NB, Ghahari F, Stroscio JA. A quantum ruler for orbital magnetism in moiré quantum matter. Science 2023; 382:81-87. [PMID: 37797004 DOI: 10.1126/science.adf2040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 08/30/2023] [Indexed: 10/07/2023]
Abstract
For almost a century, magnetic oscillations have been a powerful "quantum ruler" for measuring Fermi surface topology. In this study, we used Landau-level spectroscopy to unravel the energy-resolved valley-contrasting orbital magnetism and large orbital magnetic susceptibility that contribute to the energies of Landau levels of twisted double-bilayer graphene. These orbital magnetism effects led to substantial deviations from the standard Onsager relation, which manifested as a breakdown in scaling of Landau-level orbits. These substantial magnetic responses emerged from the nontrivial quantum geometry of the electronic structure and the large length scale of the moiré lattice potential. Going beyond traditional measurements, Landau-level spectroscopy performed with a scanning tunneling microscope offers a complete quantum ruler that resolves the full energy dependence of orbital magnetic properties in moiré quantum matter.
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Affiliation(s)
- M R Slot
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Physics, Georgetown University, Washington, DC 20007, USA
| | - Y Maximenko
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - P M Haney
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - S Kim
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Joint Quantum Institute, Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - D T Walkup
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - E Strelcov
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Son T Le
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - E M Shih
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - D Yildiz
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Joint Quantum Institute, Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - S R Blankenship
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Y Barlas
- Department of Physics, University of Nevada, Reno, NV 89557, USA
| | - N B Zhitenev
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - F Ghahari
- Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030, USA
| | - J A Stroscio
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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13
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Li Y, Wan Q, Xu N. Recent Advances in Moiré Superlattice Systems by Angle-Resolved Photoemission Spectroscopy. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2305175. [PMID: 37689836 DOI: 10.1002/adma.202305175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/16/2023] [Indexed: 09/11/2023]
Abstract
The last decade has witnessed a flourish in 2D materials including graphene and transition metal dichalcogenides (TMDs) as atomic-scale Legos. Artificial moiré superlattices via stacking 2D materials with a twist angle and/or a lattice mismatch have recently become a fertile playground exhibiting a plethora of emergent properties beyond their building blocks. These rich quantum phenomena stem from their nontrivial electronic structures that are effectively tuned by the moiré periodicity. Modern angle-resolved photoemission spectroscopy (ARPES) can directly visualize electronic structures with decent momentum, energy, and spatial resolution, thus can provide enlightening insights into fundamental physics in moiré superlattice systems and guides for designing novel devices. In this review, first, a brief introduction is given on advanced ARPES techniques and basic ideas of band structures in a moiré superlattice system. Then ARPES research results of various moiré superlattice systems are highlighted, including graphene on substrates with small lattice mismatches, twisted graphene/TMD moiré systems, and high-order moiré superlattice systems. Finally, it discusses important questions that remain open, challenges in current experimental investigations, and presents an outlook on this field of research.
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Affiliation(s)
- Yiwei Li
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, China
| | - Qiang Wan
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, China
| | - Nan Xu
- Institute for Advanced Studies (IAS), Wuhan University, Wuhan, 430072, China
- Wuhan Institute of Quantum Technology, Wuhan, 430206, China
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14
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Han X, Liu Q, Wang Y, Niu R, Qu Z, Wang Z, Li Z, Han C, Watanabe K, Taniguchi T, Song Z, Mao J, Han ZV, Gan Z, Lu J. Chemical Potential Characterization of Symmetry-Breaking Phases in a Rhombohedral Trilayer Graphene. NANO LETTERS 2023; 23:6875-6882. [PMID: 37466217 DOI: 10.1021/acs.nanolett.3c01262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
Rhombohedral trilayer graphene has recently emerged as a natural flat-band platform for studying interaction-driven symmetry-breaking phases. The displacement field (D) can further flatten the band to enhance the density of states, thereby controlling the electronic correlation that tips the energy balance between spin and valley degrees of freedom. To characterize the energy competition, chemical potential measurement─a direct thermodynamic probe of Fermi surfaces─is highly demanding to be conducted under a constant D. In this work, we characterize D-dependent isospin flavor polarization, where electronic states with isospin degeneracies of one and two can be identified. We also developed a method to measure the chemical potential at a fixed D, allowing for the extraction of energy variation during phase transitions. Furthermore, symmetry breaking could also be invoked in Landau levels, manifesting as quantum Hall ferromagnetism. Our work opens more opportunities for the thermodynamic characterization of displacement-field tuned van der Waals heterostructures.
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Affiliation(s)
- Xiangyan Han
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Qianling Liu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Yijie Wang
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Ruirui Niu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhuangzhuang Qu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhiyu Wang
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Zhuoxian Li
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Chunrui Han
- Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Zhida Song
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Jinhai Mao
- School of Physical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zheng Vitto Han
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Optoelectronics, Shanxi University, Taiyuan 030006, China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
| | - Zizhao Gan
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Jianming Lu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
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15
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Sainz-Cruz H, Pantaleón PA, Phong VT, Jimeno-Pozo A, Guinea F. Junctions and Superconducting Symmetry in Twisted Bilayer Graphene. PHYSICAL REVIEW LETTERS 2023; 131:016003. [PMID: 37478460 DOI: 10.1103/physrevlett.131.016003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 05/31/2023] [Indexed: 07/23/2023]
Abstract
Junctions provide a wealth of information on the symmetry of the order parameter of superconductors. We analyze junctions between a scanning tunneling microscope (STM) tip and superconducting twisted bilayer graphene (TBG) and TBG Josephson junctions (JJs). We compare superconducting phases that are even or odd under valley exchange (s- or f-wave). The critical current in mixed (s and f) JJs strongly depends on the angle between the junction and the lattice. In STM-TBG junctions, due to Andreev reflection, the f-wave leads to a prominent peak in subgap conductance, as seen in experiments.
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Affiliation(s)
| | | | - Võ Tiến Phong
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | | - Francisco Guinea
- Imdea Nanoscience, Faraday 9, 28015 Madrid, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastian, Spain
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16
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Talantsev EF. Intrinsic Coherence Length Anisotropy in Nickelates and Some Iron-Based Superconductors. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4367. [PMID: 37374551 DOI: 10.3390/ma16124367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/11/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023]
Abstract
Nickelate superconductors, R1-xAxNiO2 (where R is a rare earth metal and A = Sr, Ca), experimentally discovered in 2019, exhibit many unexplained mysteries, such as the existence of a superconducting state with Tc (up to 18 K) in thin films and yet absent in bulk materials. Another unexplained mystery of nickelates is their temperature-dependent upper critical field, Bc2(T), which can be nicely fitted to two-dimensional (2D) models; however, the deduced film thickness, dsc,GL, exceeds the physical film thickness, dsc, by a manifold. To address the latter, it should be noted that 2D models assume that dsc is less than the in-plane and out-of-plane ground-state coherence lengths, dsc<ξab(0) and dsc<ξc(0), respectively, and, in addition, that the inequality ξc(0)<ξab(0) satisfies. Analysis of the reported experimental Bc2(T) data showed that at least one of these conditions does not satisfy for R1-xAxNiO2 films. This implies that nickelate films are not 2D superconductors, despite the superconducting state being observed only in thin films. Based on this, here we propose an analytical three-dimensional (3D) model for a global data fit of in-plane and out-of-plane Bc2(T) in nickelates. The model is based on a heuristic expression for temperature-dependent coherence length anisotropy: γξ(T)=γξ(0)1-1a×TTc, where a>1 is a unitless free-fitting parameter. The proposed expression for γξ(T), perhaps, has a much broader application because it has been successfully applied to bulk pnictide and chalcogenide superconductors.
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Affiliation(s)
- Evgeny F Talantsev
- M. N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St., 620108 Ekaterinburg, Russia
- NANOTECH Centre, Ural Federal University, 19 Mira St., 620002 Ekaterinburg, Russia
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17
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Guo Y, Qiu D, Shao M, Song J, Wang Y, Xu M, Yang C, Li P, Liu H, Xiong J. Modulations in Superconductors: Probes of Underlying Physics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209457. [PMID: 36504310 DOI: 10.1002/adma.202209457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/16/2022] [Indexed: 06/02/2023]
Abstract
The importance of modulations is elevated to an unprecedented level, due to the delicate conditions required to bring out exotic phenomena in quantum materials, such as topological materials, magnetic materials, and superconductors. Recently, state-of-the-art modulation techniques in material science, such as electric-double-layer transistor, piezoelectric-based strain apparatus, angle twisting, and nanofabrication, have been utilized in superconductors. They not only efficiently increase the tuning capability to the broader ranges but also extend the tuning dimensionality to unprecedented degrees of freedom, including quantum fluctuations of competing phases, electronic correlation, and phase coherence essential to global superconductivity. Here, for a comprehensive review, these techniques together with the established modulation methods, such as elemental substitution, annealing, and polarization-induced gating, are contextualized. Depending on the mechanism of each method, the modulations are categorized into stoichiometric manipulation, electrostatic gating, mechanical modulation, and geometrical design. Their recent advances are highlighted by applications in newly discovered superconductors, e.g., nickelates, Kagome metals, and magic-angle graphene. Overall, the review is to provide systematic modulations in emergent superconductors and serve as the coordinate for future investigations, which can stimulate researchers in superconductivity and other fields to perform various modulations toward a thorough understanding of quantum materials.
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Affiliation(s)
- Yehao Guo
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Dong Qiu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Mingxin Shao
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Jingyan Song
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Yang Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Minyi Xu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Chao Yang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Peng Li
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Haiwen Liu
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Jie Xiong
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
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18
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González J, Stauber T. Ising superconductivity induced from spin-selective valley symmetry breaking in twisted trilayer graphene. Nat Commun 2023; 14:2746. [PMID: 37173312 PMCID: PMC10182018 DOI: 10.1038/s41467-023-38250-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 04/17/2023] [Indexed: 05/15/2023] Open
Abstract
We show that the e-e interaction induces a strong breakdown of valley symmetry for each spin channel in twisted trilayer graphene, leading to a ground state where the two spin projections have opposite sign of the valley symmetry breaking order parameter. This leads to a spin-valley locking in which the electrons of a Cooper pair are forced to live on different Fermi lines attached to opposite valleys. Furthermore, we find an effective intrinsic spin-orbit coupling explaining the protection of the superconductivity against in-plane magnetic fields. The effect of spin-selective valley symmetry breaking is validated as it reproduces the experimental observation of the reset of the Hall density at 2-hole doping. It also implies a breakdown of the symmetry of the bands from C6 to C3, with an enhancement of the anisotropy of the Fermi lines which is at the origin of a Kohn-Luttinger (pairing) instability. The isotropy of the bands is gradually recovered, however, when the Fermi level approaches the bottom of the second valence band, explaining why the superconductivity fades away in the doping range beyond 3 holes per moiré unit cell in twisted trilayer graphene.
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Affiliation(s)
- J González
- Instituto de Estructura de la Materia, CSIC, E-28006, Madrid, Spain.
| | - T Stauber
- Instituto de Ciencia de Materiales de Madrid, CSIC, E-28049, Madrid, Spain.
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19
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Curtis JB, Poniatowski NR, Xie Y, Yacoby A, Demler E, Narang P. Stabilizing Fluctuating Spin-Triplet Superconductivity in Graphene via Induced Spin-Orbit Coupling. PHYSICAL REVIEW LETTERS 2023; 130:196001. [PMID: 37243633 DOI: 10.1103/physrevlett.130.196001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 04/11/2023] [Indexed: 05/29/2023]
Abstract
A recent experiment showed that a proximity-induced Ising spin-orbit coupling enhances the spin-triplet superconductivity in Bernal bilayer graphene. Here, we show that, due to the nearly perfect spin rotation symmetry of graphene, the fluctuations of the spin orientation of the triplet order parameter suppress the superconducting transition to nearly zero temperature. Our analysis shows that both an Ising spin-orbit coupling and an in-plane magnetic field can eliminate these low-lying fluctuations and can greatly enhance the transition temperature, consistent with the recent experiment. Our model also suggests the possible existence of a phase at small anisotropy and magnetic field which exhibits quasilong-range ordered spin-singlet charge 4e superconductivity, even while the triplet 2e superconducting order only exhibits short-ranged correlations. Finally, we discuss relevant experimental signatures.
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Affiliation(s)
- Jonathan B Curtis
- College of Letters and Science, University of California, Los Angeles, California 90095, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | | | - Yonglong Xie
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Amir Yacoby
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Eugene Demler
- Institute for Theoretical Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Prineha Narang
- College of Letters and Science, University of California, Los Angeles, California 90095, USA
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20
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Qin W, Huang C, Wolf T, Wei N, Blinov I, MacDonald AH. Functional Renormalization Group Study of Superconductivity in Rhombohedral Trilayer Graphene. PHYSICAL REVIEW LETTERS 2023; 130:146001. [PMID: 37084431 DOI: 10.1103/physrevlett.130.146001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 10/01/2022] [Accepted: 03/16/2023] [Indexed: 05/03/2023]
Abstract
We employ a functional renormalization group approach to ascertain the pairing mechanism and symmetry of the superconducting phase observed in rhombohedral trilayer graphene. Superconductivity in this system occurs in a regime of carrier density and displacement field with a weakly distorted annular Fermi sea. We find that repulsive Coulomb interactions can induce electron pairing on the Fermi surface by taking advantage of momentum-space structure associated with the finite width of the Fermi sea annulus. The degeneracy between spin-singlet and spin-triplet pairing is lifted by valley-exchange interactions that strengthen under the RG flow and develop nontrivial momentum-space structure. We find that the leading pairing instability is d-wave-like and spin singlet, and that the theoretical phase diagram versus carrier density and displacement field agrees qualitatively with experiment.
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Affiliation(s)
- Wei Qin
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
| | - Chunli Huang
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
- Theoretical Division, T-4, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Tobias Wolf
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
| | - Nemin Wei
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
| | - Igor Blinov
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
| | - Allan H MacDonald
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
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21
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Xing F, Ji G, Li Z, Zhong W, Wang F, Liu Z, Xin W, Tian J. Preparation, properties and applications of two-dimensional superlattices. MATERIALS HORIZONS 2023; 10:722-744. [PMID: 36562255 DOI: 10.1039/d2mh01206e] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
As a combination concept of a 2D material and a superlattice, two-dimensional superlattices (2DSs) have attracted increasing attention recently. The natural advantages of 2D materials in their properties, dimension, diversity and compatibility, and their gradually improved technologies for preparation and device fabrication serve as solid foundations for the development of 2DSs. Compared with the existing 2D materials and even their heterostructures, 2DSs relate to more materials and elaborate architectures, leading to novel systems with more degrees of freedom to modulate material properties at the nanoscale. Here, three typical types of 2DSs, including the component, strain-induced and moiré superlattices, are reviewed. The preparation methods, properties and state-of-the-art applications of each type are summarized. An outlook of the challenges and future developments is also presented. We hope that this work can provide a reference for the development of 2DS-related research.
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Affiliation(s)
- Fei Xing
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo, 255049, China
| | - Guangmin Ji
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo, 255049, China
| | - Zongwen Li
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo, 255049, China
| | - Weiheng Zhong
- Key Laboratory of UV-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun, 130024, China.
| | - Feiyue Wang
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou, 510275, China
| | - Zhibo Liu
- Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, Teda Applied Physics Institute and School of Physics, Nankai University, Tianjin, 300071, China.
| | - Wei Xin
- Key Laboratory of UV-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun, 130024, China.
| | - Jianguo Tian
- Key Laboratory of Weak Light Nonlinear Photonics, Ministry of Education, Teda Applied Physics Institute and School of Physics, Nankai University, Tianjin, 300071, China.
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22
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Yankowitz M. Unravelling the magic of twisted trilayer graphene. NATURE MATERIALS 2023; 22:286-287. [PMID: 36631679 DOI: 10.1038/s41563-022-01462-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Affiliation(s)
- Matthew Yankowitz
- Department of Physics, University of Washington, Seattle, WA, USA.
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA.
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23
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Shen C, Ledwith PJ, Watanabe K, Taniguchi T, Khalaf E, Vishwanath A, Efetov DK. Dirac spectroscopy of strongly correlated phases in twisted trilayer graphene. NATURE MATERIALS 2023; 22:316-321. [PMID: 36550373 DOI: 10.1038/s41563-022-01428-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 11/02/2022] [Indexed: 06/17/2023]
Abstract
Magic-angle twisted trilayer graphene (MATTG) hosts flat electronic bands, and exhibits correlated quantum phases with electrical tunability. In this work, we demonstrate a spectroscopy technique that allows for dissociation of intertwined bands and quantification of the energy gaps and Chern numbers C of the correlated states in MATTG by driving band crossings between Dirac cone Landau levels and energy gaps in the flat bands. We uncover hard correlated gaps with C = 0 at integer moiré unit cell fillings of ν = 2 and 3 and reveal charge density wave states originating from van Hove singularities at fractional fillings ν = 5/3 and 11/3. In addition, we demonstrate displacement-field-driven first-order phase transitions at charge neutrality and ν = 2, which are consistent with a theoretical strong-coupling analysis, implying C2T symmetry breaking. Overall, these properties establish a diverse electrically tunable phase diagram of MATTG and provide an avenue for investigating other related systems hosting both steep and flat bands.
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Affiliation(s)
- Cheng Shen
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain.
| | | | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Japan
| | | | - Eslam Khalaf
- Department of Physics, Harvard University, Cambridge, MA, USA
| | | | - Dmitri K Efetov
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain.
- Fakultät für Physik, Ludwig-Maximilians-Universität, Schellingstrasse 4, 80799 München, Germany.
- Munich Center for Quantum Science and Technology (MCQST), München, Germany.
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24
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Veyrat A, Labracherie V, Bashlakov DL, Caglieris F, Facio JI, Shipunov G, Charvin T, Acharya R, Naidyuk Y, Giraud R, van den Brink J, Büchner B, Hess C, Aswartham S, Dufouleur J. Berezinskii-Kosterlitz-Thouless Transition in the Type-I Weyl Semimetal PtBi 2. NANO LETTERS 2023; 23:1229-1235. [PMID: 36720048 DOI: 10.1021/acs.nanolett.2c04297] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Symmetry breaking in topological matter has become in recent years a key concept in condensed matter physics to unveil novel electronic states. In this work, we predict that broken inversion symmetry and strong spin-orbit coupling in trigonal PtBi2 lead to a type-I Weyl semimetal band structure. Transport measurements show an unusually robust low dimensional superconductivity in thin exfoliated flakes up to 126 nm in thickness (with Tc ∼ 275-400 mK), which constitutes the first report and study of unambiguous superconductivity in a type-I Weyl semimetal. Remarkably, a Berezinskii-Kosterlitz-Thouless transition with TBKT ∼ 310 mK is revealed in up to 60 nm thick flakes, which is nearly an order of magnitude thicker than the rare examples of two-dimensional superconductors exhibiting such a transition. This makes PtBi2 an ideal platform to study low dimensional and unconventional superconductivity in topological semimetals.
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Affiliation(s)
- Arthur Veyrat
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
| | - Valentin Labracherie
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
| | - Dima L Bashlakov
- B. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine (NASU), 47 Nauky Avenue, 61103Kharkiv, Ukraine
| | - Federico Caglieris
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
- CNR-SPIN, Corso Perrone 24, 16152Genova, Italy
- Department of Physics, University of Genoa, Via Dodecaneso 33, 16146Genova, Italy
| | - Jorge I Facio
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
- Centro Atómico Bariloche, Instituto Balseiro and Instituto de Nanociencia y Nanotecnología CNEA-CONICET, CNEA, 8400Bariloche, Argentina
| | - Grigory Shipunov
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
| | - Titouan Charvin
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
| | - Rohith Acharya
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
| | - Yurii Naidyuk
- B. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine (NASU), 47 Nauky Avenue, 61103Kharkiv, Ukraine
| | - Romain Giraud
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
- Université Grenoble Alpes, CNRS, CEA, Grenoble-INP, Spintec, F-38000Grenoble, France
| | - Jeroen van den Brink
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
| | - Bernd Büchner
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
- Department of Physics, TU Dresden, D-01062Dresden, Germany
| | - Christian Hess
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
- Center for Transport and Devices, TU Dresden, D-01069Dresden, Germany
- Fakultät für Mathematik und Naturwissenschaften, Bergische Universität Wuppertal, D-42097Wuppertal, Germany
| | - Saicharan Aswartham
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
| | - Joseph Dufouleur
- Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, D-01069Dresden, Germany
- Center for Transport and Devices, TU Dresden, D-01069Dresden, Germany
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25
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Scammell HD, Scheurer MS. Tunable Superconductivity and Möbius Fermi Surfaces in an Inversion-Symmetric Twisted van der Waals Heterostructure. PHYSICAL REVIEW LETTERS 2023; 130:066001. [PMID: 36827571 DOI: 10.1103/physrevlett.130.066001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/11/2023] [Indexed: 06/18/2023]
Abstract
We theoretically study a moiré superlattice geometry consisting of mirror-symmetric twisted trilayer graphene surrounded by identical transition metal dichalcogenide layers. We show that this setup allows us to switch on or off and control the spin-orbit splitting of the Fermi surfaces via application of a perpendicular displacement field D_{0} and explore two manifestations of this control: first, we compute the evolution of superconducting pairing with D_{0}; this features a complex admixture of singlet and triplet pairing and, depending on the pairing state in the parent trilayer system, phase transitions between competing superconducting phases. Second, we reveal that, with application of D_{0}, the spin-orbit-induced spin textures exhibit vortices which lead to "Möbius fermi surfaces" in the interior of the Brillouin zone: diabatic electron trajectories, which are predicted to dominate quantum oscillation experiments, require encircling the Γ point twice, making their Möbius nature directly observable. Further, we show that the superconducting order parameter inherits the unconventional, Möbius spin textures. Our findings suggest that this system provides a promising experimental avenue for systematically studying the impact of spin-orbit coupling on the multitude of topological and correlated phases in near-magic-angle twisted trilayer graphene.
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Affiliation(s)
- Harley D Scammell
- School of Physics, the University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Mathias S Scheurer
- Institute for Theoretical Physics, University of Innsbruck, Innsbruck A-6020, Austria
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26
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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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27
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Poniatowski NR, Curtis JB, Bøttcher CGL, Galitski VM, Yacoby A, Narang P, Demler E. Surface Cooper-Pair Spin Waves in Triplet Superconductors. PHYSICAL REVIEW LETTERS 2022; 129:237002. [PMID: 36563226 DOI: 10.1103/physrevlett.129.237002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 08/08/2022] [Accepted: 11/10/2022] [Indexed: 06/17/2023]
Abstract
We study the electrodynamics of spin triplet superconductors including dipolar interactions, which give rise to an interplay between the collective spin dynamics of the condensate and orbital Meissner screening currents. Within this theory, we identify a class of spin waves that originate from the coupled dynamics of the spin-symmetry breaking triplet order parameter and the electromagnetic field. In particular, we study magnetostatic spin wave modes that are localized to the sample surface. We show that these surface modes can be excited and detected using experimental techniques such as microwave spin wave resonance spectroscopy or nitrogen-vacancy magnetometry, and propose that the detection of these modes offers a means for the identification of spin triplet superconductivity.
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Affiliation(s)
| | - Jonathan B Curtis
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- John A. Paulson School of Applied Sciences and Engineering, Harvard University, Cambridge, Massachusetts 02138, USA
| | | | - Victor M Galitski
- Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - Amir Yacoby
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- John A. Paulson School of Applied Sciences and Engineering, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Prineha Narang
- John A. Paulson School of Applied Sciences and Engineering, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Eugene Demler
- Institute for Theoretical Physics, ETH Zürich, 8093 Zürich, Switzerland
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28
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Huang C, Wei N, Qin W, MacDonald AH. Pseudospin Paramagnons and the Superconducting Dome in Magic Angle Twisted Bilayer Graphene. PHYSICAL REVIEW LETTERS 2022; 129:187001. [PMID: 36374687 DOI: 10.1103/physrevlett.129.187001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 07/26/2022] [Accepted: 09/23/2022] [Indexed: 06/16/2023]
Abstract
We present a theory of superconductivity in twisted bilayer graphene in which attraction is generated between electrons on the same honeycomb sublattice when the system is close to a sublattice polarization instability. The resulting Cooper pairs are spin-polarized valley singlets. Because the sublattice polarizability is mainly contributed by interband fluctuations, superconductivity occurs over a wide range of filling fraction. It is suppressed by (i) applying a sublattice polarizing field (generated by an aligned BN substrate) or (ii) changing moiré band filling to favor valley polarization. The enhanced intrasublattice attraction close to sublattice polarization instability is analogous to enhanced like-spin attraction in liquid ^{3}He near the melting curve and the enhanced valley-singlet repulsion close to valley-polarization instabilities is analogous to enhanced spin-singlet repulsion in metals that are close to a ferromagnetic instability. We comment on the relationship between our pseudospin paramagnon model and the rich phenomenology of superconductivity in twisted bilayer and multilayer graphene.
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Affiliation(s)
- Chunli Huang
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
| | - Nemin Wei
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
| | - Wei Qin
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
| | - Allan H MacDonald
- Department of Physics, University of Texas at Austin, Austin, Texas 78712, USA
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29
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Wang G, Chen C, Beshiwork BA, Xu B, Dong Y, Lin B. Fast proton and water transport in ceramic membrane-based magic-angle graphene. WATER RESEARCH 2022; 225:119076. [PMID: 36155004 DOI: 10.1016/j.watres.2022.119076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/26/2022] [Accepted: 09/06/2022] [Indexed: 06/16/2023]
Abstract
Ceramic membranes for energy conversion and storage devices are essential for becoming carbon neutral due to low cost and high stability, but limited by slow proton and water transport. Meanwhile magic-angle graphene with unconventional superconductivity ushers in a new era, properties research of which are in infant stage, urgently longing for specific applications. Herein, we investigate the ionic-conductivity and water-transport properties of ceramic membrane-based magic-angle graphene by choosing proton and water as a proof-of-concept for the first time, discover the twist-angle tuned proton conduction and water transport in ceramic membrane-based magic-angle graphene, demonstrate the faster proton and water transport in magic-angle graphene than that in graphene, and construct an efficient device of protonic ceramic membrane fuel cell based upon the new fast proton-conducting materials of magic-angle graphene. The proton conduction and water transport in magic-angle graphene can be easily tuned by the twist angle, explained by the corresponding potential energy surface. The smaller the twist angle is, and the faster the proton transport is. The protonic migration energy barrier in magic-angle graphene is lower by about 50% than that in graphene. Additionally, the water transport properties in magic-angle graphene can be improved by tuning twist angles. The electrode with magic-angle graphene can provide higher performance of protonic ceramic membrane fuel cells. The present work opens the specific application of ceramic membrane-based magic-angle graphene as new proton-conducting and water-transport materials in energy and environment.
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Affiliation(s)
- Guoqing Wang
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Chen Chen
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Bayu Admasu Beshiwork
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Bo Xu
- Department of Physics, Laboratory of Computational Materials Physics, Jiangxi Normal University, Nanchang 330022, China
| | - Yingchao Dong
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
| | - Bin Lin
- School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
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30
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Li Y, Zhang S, Chen F, Wei L, Zhang Z, Xiao H, Gao H, Chen M, Liang S, Pei D, Xu L, Watanabe K, Taniguchi T, Yang L, Miao F, Liu J, Cheng B, Wang M, Chen Y, Liu Z. Observation of Coexisting Dirac Bands and Moiré Flat Bands in Magic-Angle Twisted Trilayer Graphene. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2205996. [PMID: 36043946 DOI: 10.1002/adma.202205996] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/10/2022] [Indexed: 06/15/2023]
Abstract
Moiré superlattices that consist of two or more layers of 2D materials stacked together with a small twist angle have emerged as a tunable platform to realize various correlated and topological phases, such as Mott insulators, unconventional superconductivity, and quantum anomalous Hall effect. Recently, magic-angle twisted trilayer graphene (MATTG) has shown both robust superconductivity similar to magic-angle twisted bilayer graphene and other unique properties, including the Pauli-limit violating and re-entrant superconductivity. These rich properties are deeply rooted in its electronic structure under the influence of distinct moiré potential and mirror symmetry. Here, combining nanometer-scale spatially resolved angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy, the as-yet unexplored band structure of MATTG near charge neutrality is systematically measured. These measurements reveal the coexistence of the distinct dispersive Dirac band with the emergent moiré flat band, showing nice agreement with the theoretical calculations. These results serve as a stepstone for further understanding of the unconventional superconductivity in MATTG.
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Affiliation(s)
- Yiwei Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- Institute for Advanced Studies, Wuhan University, Luojiashan Street, Wuhan, Hubei, 430072, P. R. China
| | - Shihao Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
| | - Fanqiang Chen
- National Laboratory of Solid State Microstructures, School of Physics, Institute of Brain-Inspired Intelligence, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Liyang Wei
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
| | - Zonglin Zhang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
| | - Hanbo Xiao
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
| | - Han Gao
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
| | - Moyu Chen
- National Laboratory of Solid State Microstructures, School of Physics, Institute of Brain-Inspired Intelligence, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Shijun Liang
- National Laboratory of Solid State Microstructures, School of Physics, Institute of Brain-Inspired Intelligence, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Ding Pei
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
| | - Lixuan Xu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, P. R. China
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Lexian Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, P. R. China
- Frontier Science Center for Quantum Information, Beijing, 100084, P. R. China
| | - Feng Miao
- National Laboratory of Solid State Microstructures, School of Physics, Institute of Brain-Inspired Intelligence, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Jianpeng Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
| | - Bin Cheng
- Institute of Interdisciplinary Physical Sciences, School of Science, Nanjing University of Science and Technology, Nanjing, 210094, P. R. China
| | - Meixiao Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
| | - Yulin Chen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, P. R. China
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
| | - Zhongkai Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, P. R. China
- ShanghaiTech Laboratory for Topological Physics, Shanghai, 200031, P. R. China
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31
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Zhang Y, Polski R, Lewandowski C, Thomson A, Peng Y, Choi Y, Kim H, Watanabe K, Taniguchi T, Alicea J, von Oppen F, Refael G, Nadj-Perge S. Promotion of superconductivity in magic-angle graphene multilayers. Science 2022; 377:1538-1543. [PMID: 36173835 DOI: 10.1126/science.abn8585] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Graphene moiré superlattices show an abundance of correlated insulating, topological, and superconducting phases. Whereas the origins of strong correlations and nontrivial topology can be directly linked to flat bands, the nature of superconductivity remains enigmatic. We demonstrate that magic-angle devices made of twisted tri-, quadri-, and pentalayer graphene placed on monolayer tungsten diselenide exhibit flavor polarization and superconductivity. We also observe insulating states in the tril- and quadrilayer arising at finite electric displacement fields. As the number of layers increases, superconductivity emerges over an enhanced filling-factor range, and in the pentalayer it extends well beyond the filling of four electrons per moiré unit cell. Our results highlight the role of the interplay between flat and more dispersive bands in extending superconducting regions in graphene moiré superlattices.
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Affiliation(s)
- Yiran Zhang
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Robert Polski
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Cyprian Lewandowski
- Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Alex Thomson
- Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, University of California, Davis, CA 95616, USA
| | - Yang Peng
- Department of Physics and Astronomy, California State University, Northridge, CA 91330, USA
| | - Youngjoon Choi
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Hyunjin Kim
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Kenji Watanabe
- National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305 0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305 0044, Japan
| | - Jason Alicea
- Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Felix von Oppen
- Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Gil Refael
- Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Stevan Nadj-Perge
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, Department of Physics, California Institute of Technology, Pasadena, CA 91125, USA
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32
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Hong JP, Soejima T, Zaletel MP. Detecting Symmetry Breaking in Magic Angle Graphene Using Scanning Tunneling Microscopy. PHYSICAL REVIEW LETTERS 2022; 129:147001. [PMID: 36240422 DOI: 10.1103/physrevlett.129.147001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 08/20/2022] [Accepted: 08/25/2022] [Indexed: 06/16/2023]
Abstract
A growing body of experimental work suggests that magic angle twisted bilayer graphene exhibits a "cascade" of spontaneous symmetry-breaking transitions, sparking interest in the potential relationship between symmetry breaking and superconductivity. However, it has proven difficult to find experimental probes which can unambiguously identify the nature of the symmetry breaking. Here, we show how atomically resolved scanning tunneling microscopy can be used as a fingerprint of symmetry-breaking order. By analyzing the pattern of sublattice polarization and "Kekulé" distortions in small magnetic fields, order parameters for each of the most competitive symmetry-breaking states can be identified. In particular, we show that the "Kramers intervalley coherent state," which theoretical work predicts to be the ground state at even integer fillings, shows a Kekulé distortion which emerges only in a magnetic field.
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Affiliation(s)
- Jung Pyo Hong
- Department of Physics, Princeton University, Princeton, New Jersey 08540, USA
| | - Tomohiro Soejima
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Michael P Zaletel
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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33
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Li Y, Xiang C, Chiabrera FM, Yun S, Zhang H, Kelly DJ, Dahm RT, Kirchert CKR, Cozannet TEL, Trier F, Christensen DV, Booth TJ, Simonsen SB, Kadkhodazadeh S, Jespersen TS, Pryds N. Stacking and Twisting of Freestanding Complex Oxide Thin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2203187. [PMID: 35901262 DOI: 10.1002/adma.202203187] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/26/2022] [Indexed: 06/15/2023]
Abstract
The integration of dissimilar materials in heterostructures has long been a cornerstone of modern materials science-seminal examples are 2D materials and van der Waals heterostructures. Recently, new methods have been developed that enable the realization of ultrathin freestanding oxide films approaching the 2D limit. Oxides offer new degrees of freedom, due to the strong electronic interactions, especially the 3d orbital electrons, which give rise to rich exotic phases. Inspired by this progress, a new platform for assembling freestanding oxide thin films with different materials and orientations into artificial stacks with heterointerfaces is developed. It is shown that the oxide stacks can be tailored by controlling the stacking sequences, as well as the twist angle between the constituent layers with atomically sharp interfaces, leading to distinct moiré patterns in the transmission electron microscopy images of the full stacks. Stacking and twisting is recognized as a key degree of structural freedom in 2D materials but, until now, has never been realized for oxide materials. This approach opens unexplored avenues for fabricating artificial 3D oxide stacking heterostructures with freestanding membranes across a broad range of complex oxide crystal structures with functionalities not available in conventional 2D materials.
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Affiliation(s)
- Ying Li
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
- Hubei Province Key Laboratory of Systems Science in Metallurgical Process, Faculty of Science, Wuhan University of Science and Technology, Wuhan, 430081, P. R. China
| | - Cheng Xiang
- Department of Physics, Centre for Nanostructured Graphene (CNG), Technical University of Denmark (DTU), Fysikvej, 309, Kgs. Lyngby, 2800, Denmark
| | - Francesco M Chiabrera
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Shinhee Yun
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Haiwu Zhang
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Daniel J Kelly
- DTU Nanolab, Technical University of Denmark (DTU), Fysikvej, 307, Kgs. Lyngby, 2800, Denmark
| | - Rasmus T Dahm
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Charline K R Kirchert
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Thomas E Le Cozannet
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Felix Trier
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Dennis V Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Timothy J Booth
- Department of Physics, Centre for Nanostructured Graphene (CNG), Technical University of Denmark (DTU), Fysikvej, 309, Kgs. Lyngby, 2800, Denmark
| | - Søren B Simonsen
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Shima Kadkhodazadeh
- DTU Nanolab, Technical University of Denmark (DTU), Fysikvej, 307, Kgs. Lyngby, 2800, Denmark
| | - Thomas S Jespersen
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
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34
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Burg GW, Khalaf E, Wang Y, Watanabe K, Taniguchi T, Tutuc E. Emergence of correlations in alternating twist quadrilayer graphene. NATURE MATERIALS 2022; 21:884-889. [PMID: 35798944 DOI: 10.1038/s41563-022-01286-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
Alternating twist multilayer graphene (ATMG) has recently emerged as a family of moiré systems that share several fundamental properties with twisted bilayer graphene, and are expected to host similarly strong electron-electron interactions near the magic angle. Here, we study alternating twist quadrilayer graphene (ATQG) samples with twist angles of 1.96° and 1.52°, which are slightly removed from the magic angle of 1.68°. At the larger angle, we find signatures of correlated insulators only when the ATQG is hole doped, and no signatures of superconductivity, and for the smaller angle we find evidence of superconductivity, while signs of the correlated insulators weaken. Our results provide insight into the twist angle dependence of correlated phases in ATMG and shed light on the nature of correlations in the intermediate coupling regime at the edge of the magic angle range where dispersion and interaction are of the same order.
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Affiliation(s)
- G William Burg
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Eslam Khalaf
- Department of Physics, Harvard University, Cambridge, MA, USA
- Department of Physics, The University of Texas at Austin, Austin, TX, USA
| | - Yimeng Wang
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute of Materials Science, Ibaraki, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute of Materials Science, Ibaraki, Japan
| | - Emanuel Tutuc
- Microelectronics Research Center, Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, USA.
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35
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Park JM, Cao Y, Xia LQ, Sun S, Watanabe K, Taniguchi T, Jarillo-Herrero P. Robust superconductivity in magic-angle multilayer graphene family. NATURE MATERIALS 2022; 21:877-883. [PMID: 35798945 DOI: 10.1038/s41563-022-01287-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
The discovery of correlated states and superconductivity in magic-angle twisted bilayer graphene (MATBG) established a new platform to explore interaction-driven and topological phenomena. However, despite multitudes of correlated phases observed in moiré systems, robust superconductivity appears the least common, found only in MATBG and more recently in magic-angle twisted trilayer graphene. Here we report the experimental realization of superconducting magic-angle twisted four-layer and five-layer graphene, hence establishing alternating twist magic-angle multilayer graphene as a robust family of moiré superconductors. This finding suggests that the flat bands shared by the members play a central role in the superconductivity. Our measurements in parallel magnetic fields, in particular the investigation of Pauli limit violation and spontaneous rotational symmetry breaking, reveal a clear distinction between the N = 2 and N > 2-layer structures, consistent with the difference between their orbital responses to magnetic fields. Our results expand the emergent family of moiré superconductors, providing new insight with potential implications for design of new superconducting materials platforms.
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Affiliation(s)
- Jeong Min Park
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Yuan Cao
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Li-Qiao Xia
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Shuwen Sun
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Japan
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36
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Pesquera D, Fernández A, Khestanova E, Martin LW. Freestanding complex-oxide membranes. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:383001. [PMID: 35779514 DOI: 10.1088/1361-648x/ac7dd5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 07/01/2022] [Indexed: 06/15/2023]
Abstract
Complex oxides show a vast range of functional responses, unparalleled within the inorganic solids realm, making them promising materials for applications as varied as next-generation field-effect transistors, spintronic devices, electro-optic modulators, pyroelectric detectors, or oxygen reduction catalysts. Their stability in ambient conditions, chemical versatility, and large susceptibility to minute structural and electronic modifications make them ideal subjects of study to discover emergent phenomena and to generate novel functionalities for next-generation devices. Recent advances in the synthesis of single-crystal, freestanding complex oxide membranes provide an unprecedented opportunity to study these materials in a nearly-ideal system (e.g. free of mechanical/thermal interaction with substrates) as well as expanding the range of tools for tweaking their order parameters (i.e. (anti-)ferromagnetic, (anti-)ferroelectric, ferroelastic), and increasing the possibility of achieving novel heterointegration approaches (including interfacing dissimilar materials) by avoiding the chemical, structural, or thermal constraints in synthesis processes. Here, we review the recent developments in the fabrication and characterization of complex-oxide membranes and discuss their potential for unraveling novel physicochemical phenomena at the nanoscale and for further exploiting their functionalities in technologically relevant devices.
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Affiliation(s)
- David Pesquera
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST Campus UAB, Bellaterra, Barcelona 08193, Spain
| | - Abel Fernández
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, United States of America
| | | | - Lane W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, United States of America
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States of America
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37
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Niknam Z, Hosseinzadeh F, Shams F, Fath-Bayati L, Nuoroozi G, Mohammadi Amirabad L, Mohebichamkhorami F, Khakpour Naeimi S, Ghafouri-Fard S, Zali H, Tayebi L, Rasmi Y. Recent advances and challenges in graphene-based nanocomposite scaffolds for tissue engineering application. J Biomed Mater Res A 2022; 110:1695-1721. [PMID: 35762460 DOI: 10.1002/jbm.a.37417] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 05/22/2022] [Accepted: 06/08/2022] [Indexed: 02/06/2023]
Abstract
Graphene-based nanocomposites have recently attracted increasing attention in tissue engineering because of their extraordinary features. These biocompatible substances, in the presence of an apt microenvironment, can stimulate and sustain the growth and differentiation of stem cells into different lineages. This review discusses the characteristics of graphene and its derivatives, such as their excellent electrical signal transduction, carrier mobility, outstanding mechanical strength with improving surface characteristics, self-lubrication, antiwear properties, enormous specific surface area, and ease of functional group modification. Moreover, safety issues in the application of graphene and its derivatives in terms of biocompatibility, toxicity, and interaction with immune cells are discussed. We also describe the applicability of graphene-based nanocomposites in tissue healing and organ regeneration, particularly in the bone, cartilage, teeth, neurons, heart, skeletal muscle, and skin. The impacts of special textural and structural characteristics of graphene-based nanomaterials on the regeneration of various tissues are highlighted. Finally, the present review gives some hints on future research for the transformation of these exciting materials in clinical studies.
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Affiliation(s)
- Zahra Niknam
- Neurophysiology Research Center, Cellular and Molecular Medicine Institute, Urmia University of Medical Sciences, Urmia, Iran.,Proteomics Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Faezeh Hosseinzadeh
- Department of Tissue Engineering, Qom University of Medical Science, Qom, Iran.,Cellular and Molecular Research Center, Qom University of Medical Sciences, Qom, Iran
| | - Forough Shams
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Leyla Fath-Bayati
- Department of Tissue Engineering, Qom University of Medical Science, Qom, Iran
| | - Ghader Nuoroozi
- Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Fariba Mohebichamkhorami
- Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Soudeh Ghafouri-Fard
- Department of Medical Genetics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hakimeh Zali
- Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Medical Nanotechnology and Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Lobat Tayebi
- Marquette University School of Dentistry, Milwaukee, Wisconsin, USA
| | - Yousef Rasmi
- Department of Clinical Biochemistry, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran.,Cellular and Molecular Research Center, Cellular and Molecular Medicine Institute, Urmia University of Medical Sciences, Urmia, Iran
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38
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Talantsev EF. Method to extracting the penetration field in superconductors from DC magnetization data. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:053912. [PMID: 35649804 DOI: 10.1063/5.0081288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
The lower critical field, Bc1, is one of the fundamental quantities of a superconductor that directly manifests the Cooper pair bulk density in the material. Although this field can be measured using several techniques, the most conventional method is to calculate this field from the experimentally measured DC penetration field, Bp, which is defined as the starting point of the deviation of the DC magnetization curve, M(Bappl), from a linear dependence. Surprisingly, we found no mathematical routine that describes how this starting point of deviation can be found. Here, we propose the extraction of Bp from the fit of the M(Bappl) dataset to the power law, where the threshold criterion Mc can be established by a convention. The advantage of this approach is that the procedure extracts one additional characteristic parameter: the power-law exponent. We demonstrated the applicability of this approach to polycrystalline ThIr3, WB4.2, BaTi2Bi2O, and Th4H15; thin films of Pb and MgB2; and Nb single crystal. In most reports, Bc1(T) analysis is limited by the extraction of the London penetration depth. We advanced the analysis to extract primary thermodynamic superconducting parameters [i.e., the ground state superconducting energy gap, Δ(0); the relative jump in electronic specific heat at transition temperature, ΔCγTc; and the gap-to-transition temperature ratio, 2Δ0kBTc] from Bc1(T) data. This extraction was performed for Nb, ThIr3, TaRh2B2, and NbRh2B2.
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Affiliation(s)
- Evgueni F Talantsev
- M.N. Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18, S. Kovalevskoy St., Ekaterinburg 620108, Russia
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39
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Aoki D, Brison JP, Flouquet J, Ishida K, Knebel G, Tokunaga Y, Yanase Y. Unconventional superconductivity in UTe 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:243002. [PMID: 35203074 DOI: 10.1088/1361-648x/ac5863] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 02/24/2022] [Indexed: 06/14/2023]
Abstract
The novel spin-triplet superconductor candidate UTe2was discovered only recently at the end of 2018 and already attracted enormous attention. We review key experimental and theoretical progress which has been achieved in different laboratories. UTe2is a heavy-fermion paramagnet, but following the discovery of superconductivity, it has been expected to be close to a ferromagnetic instability, showing many similarities to the U-based ferromagnetic superconductors, URhGe and UCoGe. This view might be too simplistic. The competition between different types of magnetic interactions and the duality between the local and itinerant character of the 5fUranium electrons, as well as the shift of the U valence appear as key parameters in the rich phase diagrams discovered recently under extreme conditions like low temperature, high magnetic field, and pressure. We discuss macroscopic and microscopic experiments at low temperature to clarify the normal phase properties at ambient pressure for field applied along the three axis of this orthorhombic structure. Special attention will be given to the occurrence of a metamagnetic transition atHm= 35 T for a magnetic field applied along the hard magnetic axisb. Adding external pressure leads to strong changes in the magnetic and electronic properties with a direct feedback on superconductivity. Attention is paid on the possible evolution of the Fermi surface as a function of magnetic field and pressure. Superconductivity in UTe2is extremely rich, exhibiting various unconventional behaviors which will be highlighted. It shows an exceptionally huge superconducting upper critical field with a re-entrant behavior under magnetic field and the occurrence of multiple superconducting phases in the temperature-field-pressure phase diagrams. There is evidence for spin-triplet pairing. Experimental indications exist for chiral superconductivity and spontaneous time reversal symmetry breaking in the superconducting state. Different theoretical approaches will be described. Notably we discuss that UTe2is a possible example for the realization of a fascinating topological superconductor. Exploring superconductivity in UTe2reemphasizes that U-based heavy fermion compounds give unique examples to study and understand the strong interplay between the normal and superconducting properties in strongly correlated electron systems.
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Affiliation(s)
- D Aoki
- IMR, Tohoku University, Oarai, Ibaraki, 311-1313, Japan
| | - J-P Brison
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, F-38000 Grenoble, France
| | - J Flouquet
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, F-38000 Grenoble, France
| | - K Ishida
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - G Knebel
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, F-38000 Grenoble, France
| | - Y Tokunaga
- ASRC, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Y Yanase
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- Institute for Molecular Science, Okazaki 444-8585, Japan
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40
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Turkel S, Swann J, Zhu Z, Christos M, Watanabe K, Taniguchi T, Sachdev S, Scheurer MS, Kaxiras E, Dean CR, Pasupathy AN. Orderly disorder in magic-angle twisted trilayer graphene. Science 2022; 376:193-199. [PMID: 35389784 DOI: 10.1126/science.abk1895] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Magic-angle twisted trilayer graphene (TTG) has recently emerged as a platform to engineer strongly correlated flat bands. We reveal the normal-state structural and electronic properties of TTG using low-temperature scanning tunneling microscopy at twist angles for which superconductivity has been observed. Real trilayer samples undergo a strong reconstruction of the moiré lattice, which locks layers into near-magic-angle, mirror symmetric domains comparable in size with the superconducting coherence length. This relaxation introduces an array of localized twist-angle faults, termed twistons and moiré solitons, whose electronic structure deviates strongly from the background regions, leading to a doping-dependent, spatially granular electronic landscape. The Fermi-level density of states is maximally uniform at dopings for which superconductivity has been observed in transport measurements.
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Affiliation(s)
- Simon Turkel
- Department of Physics, Columbia University, New York, NY 10027, USA
| | - Joshua Swann
- Department of Physics, Columbia University, New York, NY 10027, USA
| | - Ziyan Zhu
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Maine Christos
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Subir Sachdev
- Department of Physics, Harvard University, Cambridge, MA 02138, USA.,School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540, USA
| | - Mathias S Scheurer
- Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Efthimios Kaxiras
- Department of Physics, Harvard University, Cambridge, MA 02138, USA.,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Cory R Dean
- Department of Physics, Columbia University, New York, NY 10027, USA
| | - Abhay N Pasupathy
- Department of Physics, Columbia University, New York, NY 10027, USA.,Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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41
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Zhou H, Holleis L, Saito Y, Cohen L, Huynh W, Patterson CL, Yang F, Taniguchi T, Watanabe K, Young AF. Isospin magnetism and spin-polarized superconductivity in Bernal bilayer graphene. Science 2022; 375:774-778. [PMID: 35025604 DOI: 10.1126/science.abm8386] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In conventional superconductors, Cooper pairing occurs between electrons of opposite spin. We observe spin-polarized superconductivity in Bernal bilayer graphene when doped to a saddle-point van Hove singularity generated by a large applied perpendicular electric field. We observe a cascade of electrostatic gate-tuned transitions between electronic phases distinguished by their polarization within the isospin space defined by the combination of the spin and momentum-space valley degrees of freedom. Although all of these phases are metallic at zero magnetic field, we observe a transition to a superconducting state at finite magnetic field B‖ ≈ 150 milliteslas applied parallel to the two-dimensional sheet. Superconductivity occurs near a symmetry-breaking transition and exists exclusively above the B‖ limit expected of a paramagnetic superconductor with the observed transition critical temperature TC ≈ 30 millikelvins, consistent with a spin-triplet order parameter.
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Affiliation(s)
- Haoxin Zhou
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Ludwig Holleis
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Yu Saito
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Liam Cohen
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - William Huynh
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Caitlin L Patterson
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Fangyuan Yang
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Andrea F Young
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
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42
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Hao T, Hao T. Quantized conductance and superconductivity of twisted graphene and other 2D crystals explained with the Eyring’s rate process theory and free volume concept. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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43
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Wang X, Cui Y, Zhang L, Yang M. Interlayer electron flow and field shielding in twisted trilayer graphene quantum dots. NANOSCALE 2022; 14:1310-1317. [PMID: 35006227 DOI: 10.1039/d1nr06808c] [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
While multilayer graphene (MLG) possesses excellent intralayer electron mobility, its interlayer electrical conductance exhibits great diversity that results in exotic phenomena and various applications in electronic devices. Driven by a vertical electric field, electron flow occurs across the layers, and its current is tunable by controlling the interlayer stacking and distance, disc size and field strength. The electron rearrangement induced by the external field is appropriately described by the polarizability that measures the electronic response against the applied field. Based on the field-induced electron density variations computed with a first-principles approach, a polarizability decomposition scheme is developed in this work to isolate the inter- and intra-layer contributions from the total polarizability of twisted trilayer graphene (TTG) quantum dots. The inter- and intra-layer counterparts reflect the charge transfer (CT) and field shielding effects among the layers, respectively. Shielded by the top and bottom layers, the middle layer is particularly effective in bridging, switching and promoting the interlayer electron flow. Large CT and shielding effects occur not only in the strongly coupled Bernal stacking, but also in the structures misorientating from the full-AAA stacking by a small twist angle. Moreover, both effects vary with the twist angle and disc size, indicating a controllable conductive/dielectric conversion in the vertical direction. In light of inter- and intralayer polarizability, our study addresses the precise modulation of interlayer conductance for TTG quantum dots, which is required in the microstructure design and performance manipulation of MLG-based electronic devices.
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Affiliation(s)
- Xian Wang
- Institute of Atomic and Molecular Physics, Key Laboratory of High Energy Density Physics of Ministry of Education, Sichuan University, Chengdu 610065, China.
| | - Yingqi Cui
- School of Physics and Electronic Engineering, Zhengzhou Normal University, Zhengzhou 450044, China
| | - Li Zhang
- Institute of Atomic and Molecular Physics, Key Laboratory of High Energy Density Physics of Ministry of Education, Sichuan University, Chengdu 610065, China.
| | - Mingli Yang
- Institute of Atomic and Molecular Physics, Key Laboratory of High Energy Density Physics of Ministry of Education, Sichuan University, Chengdu 610065, China.
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44
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Gao J, Wang C, Wang C, Chu Y, Wang S, Sun MY, Ji H, Gao Y, Wang Y, Han Y, Song F, Liu H, Zhang Y, Han L. Poly-l-Lysine-Modified Graphene Field-Effect Transistor Biosensors for Ultrasensitive Breast Cancer miRNAs and SARS-CoV-2 RNA Detection. Anal Chem 2022; 94:1626-1636. [PMID: 35025203 PMCID: PMC8767657 DOI: 10.1021/acs.analchem.1c03786] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 01/04/2022] [Indexed: 11/29/2022]
Abstract
(Mi)RNAs are important biomarkers for cancers diagnosis and pandemic diseases, which require fast, ultrasensitive, and economical detection strategies to quantitatively detect exact (mi)RNAs expression levels. The novel coronavirus disease (SARS-CoV-2) has been breaking out globally, and RNA detection is the most effective way to identify the SARS-CoV-2 virus. Here, we developed an ultrasensitive poly-l-lysine (PLL)-functionalized graphene field-effect transistor (PGFET) biosensor for breast cancer miRNAs and viral RNA detection. PLL is functionalized on the channel surface of GFET to immobilize DNA probes by the electrostatic force. The results show that PGFET biosensors can achieve a (mi)RNA detection range of five orders with a detection limit of 1 fM and an entire detection time within 20 min using 2 μL of human serum and throat swab samples, which exhibits more than 113% enhancement in terms of sensitivity compared to that of GFET biosensors. The performance enhancement mechanisms of PGFET biosensors were comprehensively studied based on an electrical biosensor theoretical model and experimental results. In addition, the PGFET biosensor was applied for the breast cancer miRNA detection in actual serum samples and SARS-CoV-2 RNA detection in throat swab samples, providing a promising approach for rapid cancer diagnosis and virus screening.
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Affiliation(s)
- Jianwei Gao
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Chunhua Wang
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Chao Wang
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Yujin Chu
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Shun Wang
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Ming yuan Sun
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Hao Ji
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Yakun Gao
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Yanhao Wang
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Yingkuan Han
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Fangteng Song
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Hong Liu
- State
Key Laboratory of Crystal Materials, Shandong
University, Jinan, Shandong 250100, China
| | - Yu Zhang
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
| | - Lin Han
- Institute
of Marine Science and Technology, Shandong
University, Qingdao 266237, China
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45
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Kim JM, Haque MF, Hsieh EY, Nahid SM, Zarin I, Jeong KY, So JP, Park HG, Nam S. Strain Engineering of Low-Dimensional Materials for Emerging Quantum Phenomena and Functionalities. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021:e2107362. [PMID: 34866241 DOI: 10.1002/adma.202107362] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/11/2021] [Indexed: 06/13/2023]
Abstract
Recent discoveries of exotic physical phenomena, such as unconventional superconductivity in magic-angle twisted bilayer graphene, dissipationless Dirac fermions in topological insulators, and quantum spin liquids, have triggered tremendous interest in quantum materials. The macroscopic revelation of quantum mechanical effects in quantum materials is associated with strong electron-electron correlations in the lattice, particularly where materials have reduced dimensionality. Owing to the strong correlations and confined geometry, altering atomic spacing and crystal symmetry via strain has emerged as an effective and versatile pathway for perturbing the subtle equilibrium of quantum states. This review highlights recent advances in strain-tunable quantum phenomena and functionalities, with particular focus on low-dimensional quantum materials. Experimental strategies for strain engineering are first discussed in terms of heterogeneity and elastic reconfigurability of strain distribution. The nontrivial quantum properties of several strain-quantum coupled platforms, including 2D van der Waals materials and heterostructures, topological insulators, superconducting oxides, and metal halide perovskites, are next outlined, with current challenges and future opportunities in quantum straintronics followed. Overall, strain engineering of quantum phenomena and functionalities is a rich field for fundamental research of many-body interactions and holds substantial promise for next-generation electronics capable of ultrafast, dissipationless, and secure information processing and communications.
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Affiliation(s)
- Jin Myung Kim
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Md Farhadul Haque
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Ezekiel Y Hsieh
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Shahriar Muhammad Nahid
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Ishrat Zarin
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Kwang-Yong Jeong
- Department of Physics, Korea University, Seoul, 02841, Republic of Korea
- Department of Physics, Jeju National University, Jeju, 63243, Republic of Korea
| | - Jae-Pil So
- Department of Physics, Korea University, Seoul, 02841, Republic of Korea
| | - Hong-Gyu Park
- Department of Physics, Korea University, Seoul, 02841, Republic of Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Republic of Korea
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Seoul, 02841, Republic of Korea
| | - SungWoo Nam
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Mechanical and Aerospace Engineering, University of California Irvine, Irvine, CA, 92697, USA
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46
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Chou YZ, Wu F, Sau JD, Das Sarma S. Correlation-Induced Triplet Pairing Superconductivity in Graphene-Based Moiré Systems. PHYSICAL REVIEW LETTERS 2021; 127:217001. [PMID: 34860110 DOI: 10.1103/physrevlett.127.217001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
Motivated by the possible non-spin-singlet superconductivity in the magic-angle twisted trilayer graphene experiment, we investigate the triplet-pairing superconductivity arising from a correlation-induced spin-fermion model of Dirac fermions with spin, valley, and sublattice degrees of freedom. We find that the f-wave pairing is favored due to the valley-sublattice structure, and the superconducting state is time-reversal symmetric, fully gapped, and nontopological. With a small in-plane magnetic field, the superconducting state becomes partially polarized, and the transition temperature can be slightly enhanced. Our results apply qualitatively to Dirac fermions for the triplet-pairing superconductivity in graphene-based moiré systems, which is fundamentally distinct from triplet superconductivity in ^{3}He and ferromagnetic superconductors.
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Affiliation(s)
- Yang-Zhi Chou
- Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - Fengcheng Wu
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jay D Sau
- Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - Sankar Das Sarma
- Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
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47
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Li J, Zeng H, Zeng Z, Zeng Y, Xie T. Promising Graphene-Based Nanomaterials and Their Biomedical Applications and Potential Risks: A Comprehensive Review. ACS Biomater Sci Eng 2021; 7:5363-5396. [PMID: 34747591 DOI: 10.1021/acsbiomaterials.1c00875] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Graphene-based nanomaterials (GBNs) have been the subject of research focus in the scientific community because of their excellent physical, chemical, electrical, mechanical, thermal, and optical properties. Several studies have been conducted on GBNs, and they have provided a detailed review and summary of various applications. However, comprehensive comments on biomedical applications and potential risks and strategies to reduce toxicity are limited. In this review, we systematically summarized the following aspects of GBNs in order to fill the gaps: (1) the history, synthesis methods, structural characteristics, and surface modification; (2) the latest advances in biomedical applications (including drug/gene delivery, biosensors, bioimaging, tissue engineering, phototherapy, and antibacterial activity); and (3) biocompatibility, potential risks (toxicity in vivo/vitro and effects on human health and the environment), and strategies to reduce toxicity. Moreover, we have analyzed the challenges to be overcome in order to enhance application of GBNs in the biomedical field.
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Affiliation(s)
- Jie Li
- College of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan 611137, China.,School of Pharmacy, Hangzhou Normal University, Hangzhou, Zhejiang 311121, China.,Key Laboratory of Elemene Class Anti-Cancer Chinese Medicine of Zhejiang Province, Hangzhou, Zhejiang 311121, China.,Engineering Laboratory of Development and Application of Traditional Chinese Medicine from Zhejiang Province, Hangzhou, Zhejiang 311121, China
| | - Huamin Zeng
- Chengdu Ping An Healthcare Medical Examination Laboratory, Chengdu, Sichuan 611130, China
| | - Zhaowu Zeng
- School of Pharmacy, Hangzhou Normal University, Hangzhou, Zhejiang 311121, China.,Key Laboratory of Elemene Class Anti-Cancer Chinese Medicine of Zhejiang Province, Hangzhou, Zhejiang 311121, China.,Engineering Laboratory of Development and Application of Traditional Chinese Medicine from Zhejiang Province, Hangzhou, Zhejiang 311121, China
| | - Yiying Zeng
- School of Pharmacy, Hangzhou Normal University, Hangzhou, Zhejiang 311121, China.,Key Laboratory of Elemene Class Anti-Cancer Chinese Medicine of Zhejiang Province, Hangzhou, Zhejiang 311121, China.,Engineering Laboratory of Development and Application of Traditional Chinese Medicine from Zhejiang Province, Hangzhou, Zhejiang 311121, China
| | - Tian Xie
- College of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan 611137, China.,School of Pharmacy, Hangzhou Normal University, Hangzhou, Zhejiang 311121, China.,Key Laboratory of Elemene Class Anti-Cancer Chinese Medicine of Zhejiang Province, Hangzhou, Zhejiang 311121, China.,Engineering Laboratory of Development and Application of Traditional Chinese Medicine from Zhejiang Province, Hangzhou, Zhejiang 311121, China
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48
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Chou YZ, Wu F, Sau JD, Das Sarma S. Acoustic-Phonon-Mediated Superconductivity in Rhombohedral Trilayer Graphene. PHYSICAL REVIEW LETTERS 2021; 127:187001. [PMID: 34767382 DOI: 10.1103/physrevlett.127.187001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 09/21/2021] [Indexed: 05/27/2023]
Abstract
Motivated by the observation of two distinct superconducting phases in the moiréless ABC-stacked rhombohedral trilayer graphene, we investigate the electron-acoustic-phonon coupling as a possible pairing mechanism. We predict the existence of superconductivity with the highest T_{c}∼3 K near the Van Hove singularity. Away from the Van Hove singularity, T_{c} remains finite in a wide range of doping. In our model, the s-wave spin-singlet and f-wave spin-triplet pairings yield the same T_{c}, while other pairing states have negligible T_{c}. Our theory provides a simple explanation for the two distinct superconducting phases in the experiment and suggests that superconductivity and other interaction-driven phases (e.g., ferromagnetism) can have different origins.
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Affiliation(s)
- Yang-Zhi Chou
- Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - Fengcheng Wu
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jay D Sau
- Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - Sankar Das Sarma
- Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
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49
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Taychatanapat T. Untwisted trilayer graphene hosts superconductivity and magnetism. Nature 2021; 598:418-420. [PMID: 34667291 DOI: 10.1038/d41586-021-02773-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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50
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Malik S, Marchesan S. Growth, Properties, and Applications of Branched Carbon Nanostructures. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:2728. [PMID: 34685169 PMCID: PMC8540255 DOI: 10.3390/nano11102728] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/07/2021] [Accepted: 10/12/2021] [Indexed: 12/19/2022]
Abstract
Nanomaterials featuring branched carbon nanotubes (b-CNTs), nanofibers (b-CNFs), or other types of carbon nanostructures (CNSs) are of great interest due to their outstanding mechanical and electronic properties. They are promising components of nanodevices for a wide variety of advanced applications spanning from batteries and fuel cells to conductive-tissue regeneration in medicine. In this concise review, we describe the methods to produce branched CNSs, with particular emphasis on the most widely used b-CNTs, the experimental and theoretical studies on their properties, and the wide range of demonstrated and proposed applications, highlighting the branching structural features that ultimately allow for enhanced performance relative to traditional, unbranched CNSs.
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Affiliation(s)
- Sharali Malik
- Karlsruhe Institute of Technology, Institute of Quantum Materials and Technology, Hermann-von-Helmholtz-Platz 1, 76131 Karlsruhe, Germany
| | - Silvia Marchesan
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy;
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