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Yang Z, Fauqué B, Nomura T, Shitaokoshi T, Kim S, Chowdhury D, Pribulová Z, Kačmarčík J, Pourret A, Knebel G, Aoki D, Klein T, Maude DK, Marcenat C, Kohama Y. Unveiling the double-peak structure of quantum oscillations in the specific heat. Nat Commun 2023; 14:7006. [PMID: 37938579 PMCID: PMC10632398 DOI: 10.1038/s41467-023-42730-4] [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: 01/19/2023] [Accepted: 10/16/2023] [Indexed: 11/09/2023] Open
Abstract
Quantum oscillation phenomenon is an essential tool to understand the electronic structure of quantum matter. Here we report a systematic study of quantum oscillations in the electronic specific heat Cel in natural graphite. We show that the crossing of a single spin Landau level and the Fermi energy give rise to a double-peak structure, in striking contrast to the single peak expected from Lifshitz-Kosevich theory. Intriguingly, the double-peak structure is predicted by the kernel term for Cel/T in the free electron theory. The Cel/T represents a spectroscopic tuning fork of width 4.8kBT which can be tuned at will to resonance. Using a coincidence method, the double-peak structure can be used to accurately determine the Landé g-factors of quantum materials. More generally, the tuning fork can be used to reveal any peak in fermionic density of states tuned by magnetic field, such as Lifshitz transition in heavy-fermion compounds.
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Affiliation(s)
- Zhuo Yang
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan.
| | - Benoît Fauqué
- JEIP, USR 3573 CNRS, Collège de France, PSL Research University, 11, Place Marcelin Berthelot, 75231, Paris Cedex 05, France
| | - Toshihiro Nomura
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Takashi Shitaokoshi
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Sunghoon Kim
- Department of Physics, Cornell University, Ithaca, NY, 14853, USA
| | | | - Zuzana Pribulová
- Centre of Low Temperature Physics, Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, SK-04001, Košice, Slovakia
| | - Jozef Kačmarčík
- Centre of Low Temperature Physics, Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, SK-04001, Košice, Slovakia
| | - Alexandre Pourret
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, 38000, Grenoble, France
| | - Georg Knebel
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, 38000, Grenoble, France
| | - Dai Aoki
- Institute for Materials Research, Tohoku University, Oarai, Ibaraki, 311-1313, Japan
| | - Thierry Klein
- Univ. Grenoble Alpes, CNRS, Institut Néel, 38000, Grenoble, France
| | - Duncan K Maude
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA, 143 avenue de Rangueil, 31400, Toulouse, France
| | - Christophe Marcenat
- Univ. Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, 38000, Grenoble, France
| | - Yoshimitsu Kohama
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
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Lv M, Sun X, Chen Y, Taniguchi T, Watanabe K, Wu M, Wang J, Xue J. Spatially Resolved Polarization Manipulation of Ferroelectricity in Twisted hBN. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2203990. [PMID: 36271514 DOI: 10.1002/adma.202203990] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Robust room-temperature interfacial ferroelectricity has been formed in the 2D limit by simply twisting two atomic layers of non-ferroelectric hexagonal boron nitride (hBN). A thorough understanding of this newly discovered ferroelectric system is required. Here, twisted hBN is used as a tunneling junction and it is studied at the nanometer scale using conductive atomic force microscopy. Three properties unique to this system are discovered. First, the polarization dependence of the tunneling resistance contrasts with the conventional theory. Second, the ferroelectric domains can be controlled using mechanical stress, highlighting the original meaning of the emergent "slidetronics". Third, ferroelectric hysteresis is highly spatially dependent. The hysteresis is symmetric at the domain walls. A few nanometers away, the hysteresis shifts completely to the positive or negative side, depending on the original polarization. These findings reveal the unconventional ferroelectricity in this 2D system.
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Affiliation(s)
- Ming Lv
- School of Physical Science and Technology, ShanghaiTech University, Pudong, Shanghai, 201210, China
| | - Xinzuo Sun
- School of Physical Science and Technology, ShanghaiTech University, Pudong, Shanghai, 201210, China
| | - Yan Chen
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Hongkou, Shanghai, 200083, China
- Frontier Institute of Chip and System, Institute of Optoelectronics, Shanghai Frontier Base of Intelligent Optoelectronics and Perception, Fudan University, Shanghai, 200438, China
| | - 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
| | - Menghao Wu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Jianlu Wang
- Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Hongkou, Shanghai, 200083, China
- Frontier Institute of Chip and System, Institute of Optoelectronics, Shanghai Frontier Base of Intelligent Optoelectronics and Perception, Fudan University, Shanghai, 200438, China
| | - Jiamin Xue
- School of Physical Science and Technology, ShanghaiTech University, Pudong, Shanghai, 201210, China
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Signatures of bosonic Landau levels in a finite-momentum superconductor. Nature 2021; 599:51-56. [PMID: 34732867 DOI: 10.1038/s41586-021-03915-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 08/16/2021] [Indexed: 11/08/2022]
Abstract
Charged particles subjected to magnetic fields form Landau levels (LLs). Originally studied in the context of electrons in metals1, fermionic LLs continue to attract interest as hosts of exotic electronic phenomena2,3. Bosonic LLs are also expected to realize novel quantum phenomena4,5, but, apart from recent advances in synthetic systems6,7, they remain relatively unexplored. Cooper pairs in superconductors-composite bosons formed by electrons-represent a potential condensed-matter platform for bosonic LLs. Under certain conditions, an applied magnetic field is expected to stabilize an unusual superconductor with finite-momentum Cooper pairs8,9 and exert control over bosonic LLs10-13. Here we report thermodynamic signatures, observed by torque magnetometry, of bosonic LL transitions in the layered superconductor Ba6Nb11S28. By applying an in-plane magnetic field, we observe an abrupt, partial suppression of diamagnetism below the upper critical magnetic field, which is suggestive of an emergent phase within the superconducting state. With increasing out-of-plane magnetic field, we observe a series of sharp modulations in the upper critical magnetic field that are indicative of distinct vortex states and with a structure that agrees with predictions for Cooper pair LL transitions in a finite-momentum superconductor10-14. By applying Onsager's quantization rule15, we extract the momentum. Furthermore, study of the fermionic LLs shows evidence for a non-zero Berry phase. This suggests opportunities to study bosonic LLs, topological superconductivity, and their interplay via transport16, scattering17, scanning probe18 and exfoliation techniques19.
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Wang J, Nie P, Li X, Zuo H, Fauqué B, Zhu Z, Behnia K. Critical point for Bose-Einstein condensation of excitons in graphite. Proc Natl Acad Sci U S A 2020; 117:30215-30219. [PMID: 33199600 PMCID: PMC7720211 DOI: 10.1073/pnas.2012811117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An exciton is an electron-hole pair bound by attractive Coulomb interaction. Short-lived excitons have been detected by a variety of experimental probes in numerous contexts. An excitonic insulator, a collective state of such excitons, has been more elusive. Here, thanks to Nernst measurements in pulsed magnetic fields, we show that in graphite there is a critical temperature (T = 9.2 K) and a critical magnetic field (B = 47 T) for Bose-Einstein condensation of excitons. At this critical field, hole and electron Landau subbands simultaneously cross the Fermi level and allow exciton formation. By quantifying the effective mass and the spatial separation of the excitons in the basal plane, we show that the degeneracy temperature of the excitonic fluid corresponds to this critical temperature. This identification would explain why the field-induced transition observed in graphite is not a universal feature of three-dimensional electron systems pushed beyond the quantum limit.
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Affiliation(s)
- Jinhua Wang
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Pan Nie
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiaokang Li
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Huakun Zuo
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Benoît Fauqué
- Jeunes Équipes de l'Institut de Physique, Unité Mixte de Service et de Recherche 3573, CNRS, Collège de France, Paris Sciences et Lettres Research University, 75231 Paris Cedex 05, France
| | - Zengwei Zhu
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China;
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Kamran Behnia
- Laboratoire de Physique et d'Étude des Matériaux, CNRS, École Supérieure de Physique et de Chimie Industrielles Paris, Paris Sciences et Lettres Research University, 75005 Paris, France
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Cea T, Walet NR, Guinea F. Twists and the Electronic Structure of Graphitic Materials. NANO LETTERS 2019; 19:8683-8689. [PMID: 31743649 DOI: 10.1021/acs.nanolett.9b03335] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We analyze the effect of twists on the electronic structure of configurations of infinite stacks of graphene layers. We focus on three different cases: an infinite stack where each layer is rotated with respect to the previous one by a fixed angle, two pieces of semi-infinite graphite rotated with respect to each other, and finally a single layer of graphene rotated with respect to a graphite surface. In all three cases, we find a rich structure, with sharp resonances and flat bands for small twist angles. The method used can be easily generalized to more complex arrangements and stacking sequences.
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Affiliation(s)
- Tommaso Cea
- Imdea Nanoscience , Faraday 9 , 28015 Madrid , Spain
| | - Niels R Walet
- School of Physics and Astronomy , University of Manchester , Manchester , M13 9PY , U.K
| | - Francisco Guinea
- Imdea Nanoscience , Faraday 9 , 28015 Madrid , Spain
- School of Physics and Astronomy , University of Manchester , Manchester , M13 9PY , U.K
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6
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Zhu Z, McDonald RD, Shekhter A, Ramshaw BJ, Modic KA, Balakirev FF, Harrison N. Magnetic field tuning of an excitonic insulator between the weak and strong coupling regimes in quantum limit graphite. Sci Rep 2017; 7:1733. [PMID: 28496192 PMCID: PMC5431932 DOI: 10.1038/s41598-017-01693-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 04/03/2017] [Indexed: 11/09/2022] Open
Abstract
The excitonic insulator phase has long been predicted to form in proximity to a band gap opening in the underlying band structure. The character of the pairing is conjectured to crossover from weak (BCS-like) to strong coupling (BEC-like) as the underlying band structure is tuned from the metallic to the insulating side of the gap opening. Here we report the high-magnetic field phase diagram of graphite to exhibit just such a crossover. By way of comprehensive angle-resolved magnetoresistance measurements, we demonstrate that the underlying band gap opening occurs inside the magnetic field-induced phase, paving the way for a systematic study of the BCS-BEC-like crossover by means of conventional condensed matter probes.
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Affiliation(s)
- Z Zhu
- MS-E536, NHMFL, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA. .,Wuhan National High Magnetic Field Center, School of Physics, Huazhong University of Science and Technology, 1037 Luoyu Road, 430074, Wuhan, China.
| | - R D McDonald
- MS-E536, NHMFL, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA
| | - A Shekhter
- MS-E536, NHMFL, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.,National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, Florida, 32310, USA
| | - B J Ramshaw
- MS-E536, NHMFL, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.,Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY, 14853, USA
| | - K A Modic
- MS-E536, NHMFL, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.,Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strape 40, Presden, 01187, Germany
| | - F F Balakirev
- MS-E536, NHMFL, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA
| | - N Harrison
- MS-E536, NHMFL, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.
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Zhu Z, Lin X, Liu J, Fauqué B, Tao Q, Yang C, Shi Y, Behnia K. Quantum Oscillations, Thermoelectric Coefficients, and the Fermi Surface of Semimetallic WTe2. PHYSICAL REVIEW LETTERS 2015; 114:176601. [PMID: 25978245 DOI: 10.1103/physrevlett.114.176601] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Indexed: 06/04/2023]
Abstract
We present a study of angle-resolved quantum oscillations of electric and thermoelectric transport coefficients in semimetallic WTe2, which has the particularity of displaying a large B(2) magnetoresistance. The Fermi surface consists of two pairs of electronlike and holelike pockets of equal volumes in a "Russian doll" structure. The carrier density, Fermi energy, mobility, and the mean-free path of the system are quantified. An additional frequency is observed above a threshold field and attributed to the magnetic breakdown across two orbits. In contrast to all other dilute metals, the Nernst signal remains linear in the magnetic field even in the high-field (ωcτ≫1) regime. Surprisingly, none of the pockets extend across the c axis of the first Brillouin zone, making the system a three-dimensional metal with moderate anisotropy in Fermi velocity, yet a large anisotropy in the mean-free path.
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Affiliation(s)
- Zengwei Zhu
- Wuhan National High Magnetic Field Center, School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiao Lin
- LPEM (CNRS-UPMC), ESPCI, 75005 Paris, France
| | - Juan Liu
- Wuhan National High Magnetic Field Center, School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | | | - Qian Tao
- LPEM (CNRS-UPMC), ESPCI, 75005 Paris, France
| | - Chongli Yang
- Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Youguo Shi
- Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
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