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Ienaga K, Tamoto Y, Yoda M, Yoshimura Y, Ishigami T, Okuma S. Broadened quantum critical ground state in a disordered superconducting thin film. Nat Commun 2024; 15:2388. [PMID: 38493176 PMCID: PMC10944498 DOI: 10.1038/s41467-024-46628-7] [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: 08/25/2023] [Accepted: 02/29/2024] [Indexed: 03/18/2024] Open
Abstract
A superconductor-insulator transition (SIT) in two dimensions is a prototypical quantum phase transition (QPT) with a clear quantum critical point (QCP) at zero temperature (T = 0). The SIT is induced by a field B and observed in disordered thin films. In some of weakly disordered or crystalline thin films, however, an anomalous metallic (AM) ground state emerges over a wide B range between the superconducting and insulating phases. It remains a fundamental open question how the QPT picture of the SIT is modified when the AM state appears. Here we present measurements of the Nernst effect N, which has great sensitivity to the fluctuations of the superconducting order parameter. From a thorough contour map of N in the B-T plane, we found a thermal-to-quantum crossover line of the superconducting fluctuations, a so-called ghost-temperature line associated with the QPT, as well as a ghost-field line associated with a thermal transition. The QCP is identified as a T = 0 intercept of the ghost-temperature line inside the AM state, which verifies that the AM state is a broadened critical state of the SIT.
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Affiliation(s)
- Koichiro Ienaga
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan.
| | - Yutaka Tamoto
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Masahiro Yoda
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Yuki Yoshimura
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Takahiro Ishigami
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Satoshi Okuma
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo, 152-8551, Japan
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Wang Z, Liu Y, Ji C, Wang J. Quantum phase transitions in two-dimensional superconductors: a review on recent experimental progress. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2023; 87:014502. [PMID: 38086096 DOI: 10.1088/1361-6633/ad14f3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 12/12/2023] [Indexed: 12/30/2023]
Abstract
Superconductor-insulator/metal transition (SMT) as a paradigm of quantum phase transition has been a research highlight over the last three decades. Benefit from recent developments in the fabrication and measurements of two-dimensional (2D) superconducting films and nanodevices, unprecedented quantum phenomena have been revealed in the quantum phase transitions of 2D superconductors. In this review, we introduce the recent progress on quantum phase transitions in 2D superconductors, focusing on the quantum Griffiths singularity (QGS) and anomalous metal state. Characterized by a divergent critical exponent when approaching zero temperature, QGS of SMT is discovered in ultrathin crystalline Ga films and subsequently detected in various 2D superconductors. The universality of QGS indicates the profound influence of quenched disorder on quantum phase transitions. Besides, in a 2D superconducting system, whether a metallic ground state can exist is a long-sought mystery. Early experimental studies indicate an intermediate metallic state in the quantum phase transition of 2D superconductors. Recently, in high-temperature superconducting films with patterned nanopores, a robust anomalous metal state (i.e. quantum metal or Bose metal) has been detected, featured as the saturated resistance in the low temperature regime. Moreover, the charge-2equantum oscillations are observed in nanopatterned films, indicating the bosonic nature of the anomalous metal state and ending the debate on whether bosons can exist as a metal. The evidences of the anomalous metal states have also been reported in crystalline epitaxial thin films and exfoliated nanoflakes, as well as granular composite films. High quality filters are used in these works to exclude the influence of external high frequency noises in ultralow temperature measurements. The observations of QGS and metallic ground states in 2D superconductors not only reveal the prominent role of quantum fluctuations and dissipations but also provide new perspective to explore quantum phase transitions in superconducting systems.
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Affiliation(s)
- Ziqiao Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Yi Liu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, People's Republic of China
- Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing 100872, People's Republic of China
| | - Chengcheng Ji
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Hefei National Laboratory, Hefei 230088, People's Republic of China
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China
- Hefei National Laboratory, Hefei 230088, People's Republic of China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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3
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Cheng D, Song B, Kang JH, Sundahl C, Edgeton AL, Luo L, Park JM, Collantes YG, Hellstrom EE, Mootz M, Perakis IE, Eom CB, Wang J. Study of Elastic and Structural Properties of BaFe 2As 2 Ultrathin Film Using Picosecond Ultrasonics. MATERIALS (BASEL, SWITZERLAND) 2023; 16:7031. [PMID: 37959629 PMCID: PMC10650054 DOI: 10.3390/ma16217031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 10/30/2023] [Accepted: 10/30/2023] [Indexed: 11/15/2023]
Abstract
We obtain the through-thickness elastic stiffness coefficient (C33) in nominal 9 nm and 60 nm BaFe2As2 (Ba-122) thin films by using picosecond ultrasonics. Particularly, we reveal the increase in elastic stiffness as film thickness decreases from bulk value down to 9 nm, which we attribute to the increase in intrinsic strain near the film-substrate interface. Our density functional theory (DFT) calculations reproduce the observed acoustic oscillation frequencies well. In addition, temperature dependence of longitudinal acoustic (LA) phonon mode frequency for 9 nm Ba-122 thin film is reported. The frequency change is attributed to the change in Ba-122 orthorhombicity (a-b)/(a+b). This conclusion can be corroborated by our previous ultrafast ellipticity measurements in 9 nm Ba-122 thin film, which exhibit strong temperature dependence and indicate the structural phase transition temperature Ts.
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Affiliation(s)
- Di Cheng
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA; (D.C.); (B.S.); (L.L.); (J.-M.P.)
- Ames National Laboratory-USDOE, Ames, IA 50011, USA
| | - Boqun Song
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA; (D.C.); (B.S.); (L.L.); (J.-M.P.)
- Ames National Laboratory-USDOE, Ames, IA 50011, USA
| | - Jong-Hoon Kang
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.-H.K.); (C.S.); (A.L.E.); (C.-B.E.)
| | - Chris Sundahl
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.-H.K.); (C.S.); (A.L.E.); (C.-B.E.)
| | - Anthony L. Edgeton
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.-H.K.); (C.S.); (A.L.E.); (C.-B.E.)
| | - Liang Luo
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA; (D.C.); (B.S.); (L.L.); (J.-M.P.)
- Ames National Laboratory-USDOE, Ames, IA 50011, USA
| | - Joong-Mok Park
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA; (D.C.); (B.S.); (L.L.); (J.-M.P.)
- Ames National Laboratory-USDOE, Ames, IA 50011, USA
| | - Yesusa G. Collantes
- Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA (E.E.H.)
| | - Eric E. Hellstrom
- Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA (E.E.H.)
| | - Martin Mootz
- Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35294-1170, USA; (M.M.); (I.E.P.)
| | - Ilias E. Perakis
- Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35294-1170, USA; (M.M.); (I.E.P.)
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA; (J.-H.K.); (C.S.); (A.L.E.); (C.-B.E.)
| | - Jigang Wang
- Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA; (D.C.); (B.S.); (L.L.); (J.-M.P.)
- Ames National Laboratory-USDOE, Ames, IA 50011, USA
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Weitzel A, Pfaffinger L, Maccari I, Kronfeldner K, Huber T, Fuchs L, Mallord J, Linzen S, Il'ichev E, Paradiso N, Strunk C. Sharpness of the Berezinskii-Kosterlitz-Thouless Transition in Disordered NbN Films. PHYSICAL REVIEW LETTERS 2023; 131:186002. [PMID: 37977616 DOI: 10.1103/physrevlett.131.186002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 09/21/2023] [Indexed: 11/19/2023]
Abstract
We present a comprehensive investigation of the Berezinskii-Kosterlitz-Thouless transition in ultrathin strongly disordered NbN films. Measurements of resistance, current-voltage characteristics, and kinetic inductance on the very same device reveal a consistent picture of a sharp unbinding transition of vortex-antivortex pairs that fit standard renormalization group theory without extra assumptions in terms of inhomogeneity. Our experiments demonstrate that the previously observed broadening of the transition is not an intrinsic feature of strongly disordered superconductors and provide a clean starting point for the study of dynamical effects at the Berezinskii-Kosterlitz-Thouless transition.
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Affiliation(s)
- Alexander Weitzel
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Lea Pfaffinger
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Ilaria Maccari
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Klaus Kronfeldner
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Thomas Huber
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Lorenz Fuchs
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - James Mallord
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Sven Linzen
- Leibniz Institute of Photonic Technology, D-07745 Jena, Germany
| | - Evgeni Il'ichev
- Leibniz Institute of Photonic Technology, D-07745 Jena, Germany
| | - Nicola Paradiso
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Christoph Strunk
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
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5
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Cao Q, Telford EJ, Benyamini A, Kennedy I, Zangiabadi A, Watanabe K, Taniguchi T, Dean CR, Hunt BM. Tunneling Spectroscopy of Two-Dimensional Materials Based on Via Contacts. NANO LETTERS 2022; 22:8941-8948. [PMID: 36356229 DOI: 10.1021/acs.nanolett.2c03081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We introduce a novel planar tunneling architecture for van der Waals heterostructures based on via contacts, namely, metallic contacts embedded into through-holes in hexagonal boron nitride (hBN). We use the via-based tunneling method to study the single-particle density of states of two different two-dimensional (2D) materials, NbSe2 and graphene. In NbSe2 devices, we characterize the barrier strength and interface disorder for barrier thicknesses of 0, 1, and 2 layers of hBN and study the dependence on the tunnel-contact area down to (44 ± 14)2 nm2. For 0-layer hBN devices, we demonstrate a crossover from diffusive to point contacts in the small-contact-area limit. In graphene, we show that reducing the tunnel barrier thickness and area can suppress effects due to phonon-assisted tunneling and defects in the hBN barrier. This via-based architecture overcomes limitations of other planar tunneling designs and produces high-quality, ultraclean tunneling structures from a variety of 2D materials.
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Affiliation(s)
- Qingrui Cao
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania15213, United States
| | - Evan J Telford
- Department of Physics, Columbia University, New York, New York10027, United States
| | - Avishai Benyamini
- Department of Physics, Columbia University, New York, New York10027, United States
| | - Ian Kennedy
- Department of Physics, Columbia University, New York, New York10027, United States
| | - Amirali Zangiabadi
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York10027, United States
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, Japan
| | - Cory R Dean
- Department of Physics, Columbia University, New York, New York10027, United States
| | - Benjamin M Hunt
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania15213, United States
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6
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Ding D, Qu Z, Han X, Han C, Zhuang Q, Yu XL, Niu R, Wang Z, Li Z, Gan Z, Wu J, Lu J. Multivalley Superconductivity in Monolayer Transition Metal Dichalcogenides. NANO LETTERS 2022; 22:7919-7926. [PMID: 36173038 DOI: 10.1021/acs.nanolett.2c02947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In transition metal dichalcogenides (TMDs), Ising superconductivity with an antisymmetric spin texture on the Fermi surface has attracted wide interest due to the exotic pairing and topological properties. However, it is not clear whether the Q valley with a giant spin splitting is involved in the superconductivity of heavily doped semiconducting 2H-TMDs. Here by taking advantage of a high-quality monolayer WS2 on hexagonal boron nitride flakes, we report an ionic-gating induced superconducting dome with a record high critical temperature of ∼6 K, accompanied by an emergent nonlinear Hall effect. The nonlinearity indicates the development of an additional high-mobility channel, which (corroborated by first principle calculations) can be ascribed to the population of Q valleys. Thus, multivalley population at K and Q is suggested to be a prerequisite for developing superconductivity. The involvement of Q valleys also provides insights to the spin textured Fermi surface of Ising superconductivity in the large family of transition metal dichalcogenides.
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Affiliation(s)
- Dongdong Ding
- 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
| | - Xiangyan Han
- 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
| | - Quan Zhuang
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, China
- Inner Mongolia Key Laboratory of Carbon Nanomaterials, Nano Innovation Institute (NII), Inner Mongolia Minzu University, Tongliao 028000, China
| | - Xiang-Long Yu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Ruirui Niu
- 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
| | - Zizhao Gan
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Jiansheng Wu
- Shenzhen Institute for Quantum Science and Engineering (SIQSE), Southern University of Science and Technology, Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Jianming Lu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
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7
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Zhang X, Palevski A, Kapitulnik A. Anomalous metals: From "failed superconductor" to "failed insulator". Proc Natl Acad Sci U S A 2022; 119:e2202496119. [PMID: 35858313 PMCID: PMC9304025 DOI: 10.1073/pnas.2202496119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/26/2022] [Indexed: 01/16/2023] Open
Abstract
Resistivity saturation is found on both superconducting and insulating sides of an "avoided" magnetic-field-tuned superconductor-to-insulator transition (H-SIT) in a two-dimensional In/InOx composite, where the anomalous metallic behavior cuts off conductivity or resistivity divergence in the zero-temperature limit. The granular morphology of the material implies a system of Josephson junctions (JJs) with a broad distribution of Josephson coupling EJ and charging energy EC, with an H-SIT determined by the competition between EJ and EC. By virtue of self-duality across the true H-SIT, we invoke macroscopic quantum tunneling effects to explain the temperature-independent resistance where the "failed superconductor" side is a consequence of phase fluctuations and the "failed insulator" side results from charge fluctuations. While true self-duality is lost in the avoided transition, its vestiges are argued to persist, owing to the incipient duality of the percolative nature of the dissipative path in the underlying random JJ system.
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Affiliation(s)
- Xinyang Zhang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305
- Department of Applied Physics, Stanford University, Stanford, CA 94305
| | - Alexander Palevski
- School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Aharon Kapitulnik
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305
- Department of Applied Physics, Stanford University, Stanford, CA 94305
- Department of Physics, Stanford University, Stanford, CA 94305
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Raychaudhuri P, Dutta S. Phase fluctuations in conventional superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:083001. [PMID: 34731851 DOI: 10.1088/1361-648x/ac360b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/03/2021] [Indexed: 06/13/2023]
Abstract
Within the Bardeen-Cooper-Schrieffer (BCS) theory, superconductivity is entirely governed by the pairing energy scale, which gives rise to the superconducting energy gap, Δ. However, another important energy scale, the superfluid phase stiffness,J, which determines the resilience of the superconductor to phase-fluctuations is normally ignored. The spectacular success of BCS theory owes to the fact that in conventional superconductorsJis normally several orders of magnitude larger than Δ and thus an irrelevant energy scale. However, in certain situations such as in the presence of low carrier density, strong disorder, at low-dimensions or in granular superconductors,Jcan drastically come down and even become smaller than Δ. In such situations, the temperature and magnetic field evolution of superconducting properties is governed by phase fluctuations, which gives rise to novel electronic states where signatures of electronic pairing continue to exist even when the zero resistance state is destroyed. In this article, we will review the recent experimental developments on the study of phase fluctuations in conventional superconductors.
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Affiliation(s)
- Pratap Raychaudhuri
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Surajit Dutta
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
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Xing Y, Yang P, Ge J, Yan J, Luo J, Ji H, Yang Z, Li Y, Wang Z, Liu Y, Yang F, Qiu P, Xi C, Tian M, Liu Y, Lin X, Wang J. Extrinsic and Intrinsic Anomalous Metallic States in Transition Metal Dichalcogenide Ising Superconductors. NANO LETTERS 2021; 21:7486-7494. [PMID: 34460267 DOI: 10.1021/acs.nanolett.1c01426] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The metallic ground state in two-dimensional (2D) superconductors has attracted much attention but is still under intense scrutiny. Especially, the measurements in the ultralow temperature region are challenging for 2D superconductors due to the sensitivity to external perturbations. In this work, the resistance saturation induced by external noise, named as the "extrinsic anomalous metallic state", is observed in 2D transition metal dichalcogenide (TMD) superconductor 4Ha-TaSe2 nanodevices. However, with further decreasing temperature, credible evidence of the intrinsic anomalous metallic state is obtained by adequately filtering external radiation. Our work indicates that, at ultralow temperatures, the anomalous metallic state can be experimentally revealed as the quantum ground state in 2D crystalline TMD superconductors. Besides, Ising superconductivity revealed by ultrahigh in-plane critical field (Bc2∥) going beyond the Pauli paramagnetic limit (Bp) is detected in 4Ha-TaSe2, from the one-unit-cell device to the bulk situation, which might be due to the weak coupling between the TaSe2 submonolayers.
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Affiliation(s)
- Ying Xing
- State Key Laboratory of Heavy Oil Processing, College of New Energy and Materials, China University of Petroleum, Beijing 102249, China
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Pu Yang
- State Key Laboratory of Heavy Oil Processing, College of New Energy and Materials, China University of Petroleum, Beijing 102249, China
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jun Ge
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Jiaojie Yan
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Jiawei Luo
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Haoran Ji
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Zeyan Yang
- State Key Laboratory of Heavy Oil Processing, College of New Energy and Materials, China University of Petroleum, Beijing 102249, China
| | - Yongjie Li
- State Key Laboratory of Heavy Oil Processing, College of New Energy and Materials, China University of Petroleum, Beijing 102249, China
| | - Zijia Wang
- State Key Laboratory of Heavy Oil Processing, College of New Energy and Materials, China University of Petroleum, Beijing 102249, China
| | - Yanzhao Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Feng Yang
- State Key Laboratory of Heavy Oil Processing, College of New Energy and Materials, China University of Petroleum, Beijing 102249, China
| | - Ping Qiu
- State Key Laboratory of Heavy Oil Processing, College of New Energy and Materials, China University of Petroleum, Beijing 102249, China
| | - Chuanying Xi
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Mingliang Tian
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Yi Liu
- Department of Physics, Renmin University of China, Beijing 100872, China
| | - Xi Lin
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
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10
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Coexistence of resistance oscillations and the anomalous metal phase in a lithium intercalated TiSe 2 superconductor. Nat Commun 2021; 12:5342. [PMID: 34504094 PMCID: PMC8429654 DOI: 10.1038/s41467-021-25671-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 08/22/2021] [Indexed: 11/24/2022] Open
Abstract
Superconductivity and charge density wave (CDW) appear in the phase diagram of a variety of materials including the high-Tc cuprate family and many transition metal dichalcogenides (TMDs). Their interplay may give rise to exotic quantum phenomena. Here, we show that superconducting arrays can spontaneously form in TiSe2–a TMD with coexisting superconductivity and CDW—after lithium ion intercalation. We induce a superconducting dome in the phase diagram of LixTiSe2 by using the ionic solid-state gating technique. Around optimal doping, we observe magnetoresistance oscillations, indicating the emergence of periodically arranged domains. In the same temperature, magnetic field and carrier density regime where the resistance oscillations occur, we observe signatures for the anomalous metal—a state with a resistance plateau across a wide temperature range below the superconducting transition. Our study not only sheds further insight into the mechanism for the periodic electronic structure, but also reveals the interplay between the anomalous metal and superconducting fluctuations. The interplay between superconductivity and charge density wave (CDW) gives rise to exotic quantum phenomena. Here, the authors observe magnetoresistance oscillations and an anomalous metal state due to the coexistence of superconductivity and CDW in lithium intercalated TiSe2.
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11
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Chen Z, Liu Y, Zhang H, Liu Z, Tian H, Sun Y, Zhang M, Zhou Y, Sun J, Xie Y. Electric field control of superconductivity at the LaAlO 3/KTaO 3(111) interface. Science 2021; 372:721-724. [PMID: 33986177 DOI: 10.1126/science.abb3848] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 04/02/2021] [Indexed: 11/02/2022]
Abstract
The oxide interface between LaAlO3 and KTaO3(111) can harbor a superconducting state. We report that by applying a gate voltage (V G) across KTaO3, the interface can be continuously tuned from superconducting into insulating states, yielding a dome-shaped T c-V G dependence, where T c is the transition temperature. The electric gating has only a minor effect on carrier density but a strong one on mobility. We interpret the tuning of mobility in terms of change in the spatial profile of the carriers in the interface and hence, effective disorder. As the temperature is decreased, the resistance saturates at the lowest temperature on both superconducting and insulating sides, suggesting the emergence of a quantum metallic state associated with a failed superconductor and/or fragile insulator.
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Affiliation(s)
- Zheng Chen
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Yuan Liu
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Hui Zhang
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing, 100191, China
| | - Zhongran Liu
- Center of Electron Microscope, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - He Tian
- Center of Electron Microscope, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Yanqiu Sun
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Meng Zhang
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Yi Zhou
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. .,Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China.,Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Jirong Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. .,Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanwu Xie
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, China. .,Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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12
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Qiu D, Gong C, Wang S, Zhang M, Yang C, Wang X, Xiong J. Recent Advances in 2D Superconductors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2006124. [PMID: 33768653 DOI: 10.1002/adma.202006124] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/22/2020] [Indexed: 06/12/2023]
Abstract
The emergence of superconductivity in 2D materials has attracted much attention and there has been rapid development in recent years because of their fruitful physical properties, such as high transition temperature (Tc ), continuous phase transition, and enhanced parallel critical magnetic field (Bc ). Tremendous efforts have been devoted to exploring different physical parameters to figure out the mechanisms behind the unexpected superconductivity phenomena, including adjusting the thickness of samples, fabricating various heterostructures, tuning the carrier density by electric field and chemical doping, and so on. Here, different types of 2D superconductivity with their unique characteristics are introduced, including the conventional Bardeen-Cooper-Schrieffer superconductivity in ultrathin films, high-Tc superconductivity in Fe-based and Cu-based 2D superconductors, unconventional superconductivity in newly discovered twist-angle bilayer graphene, superconductivity with enhanced Bc , and topological superconductivity. A perspective toward this field is then proposed based on academic knowledge from the recently reported literature. The aim is to provide researchers with a clear and comprehensive understanding about the newly developed 2D superconductivity and promote the development of this field much further.
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Affiliation(s)
- Dong Qiu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Chuanhui Gong
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - SiShuang Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Miao Zhang
- 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
| | - Xianfu Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, 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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13
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Liu X, Wang Z, Watanabe K, Taniguchi T, Vafek O, Li JIA. Tuning electron correlation in magic-angle twisted bilayer graphene using Coulomb screening. Science 2021; 371:1261-1265. [PMID: 33737488 DOI: 10.1126/science.abb8754] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 02/08/2021] [Indexed: 12/24/2022]
Abstract
Controlling the strength of interactions is essential for studying quantum phenomena emerging in systems of correlated fermions. We introduce a device geometry whereby magic-angle twisted bilayer graphene is placed in close proximity to a Bernal bilayer graphene, separated by a 3-nanometer-thick barrier. By using charge screening from the Bernal bilayer, the strength of electron-electron Coulomb interaction within the twisted bilayer can be continuously tuned. Transport measurements show that tuning Coulomb screening has opposite effects on the insulating and superconducting states: As Coulomb interaction is weakened by screening, the insulating states become less robust, whereas the stability of superconductivity at the optimal doping is enhanced. The results provide important constraints on theoretical models for understanding the mechanism of superconductivity in magic-angle twisted bilayer graphene.
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Affiliation(s)
- Xiaoxue Liu
- Department of Physics, Brown University, Providence, RI 02912, USA
| | - Zhi Wang
- Department of Physics, Brown University, Providence, RI 02912, USA
| | - K Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - T Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Oskar Vafek
- Department of Physics, Florida State University, Tallahassee, FL 32306, USA.,National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | - J I A Li
- Department of Physics, Brown University, Providence, RI 02912, USA.
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14
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Benyamini A, Kennes DM, Telford EJ, Watanabe K, Taniguchi T, Millis AJ, Hone J, Dean CR, Pasupathy AN. Nonmonotonic Temperature-Dependent Dissipation at Nonequilibrium in Atomically Thin Clean-Limit Superconductors. NANO LETTERS 2021; 21:583-589. [PMID: 33372802 DOI: 10.1021/acs.nanolett.0c04024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Resistance in superconductors arises from the motion of vortices driven by flowing supercurrents or external electromagnetic fields and may be strongly affected by thermal or quantum fluctuations. The common expectation is that as the temperature is lowered, vortex motion is suppressed, leading to a decreased resistance. We show experimentally that in clean-limit atomically thin 2H-NbSe2 the resistance below the superconducting transition temperature may be nonmonotonic, passing through a minimum before increasing again as the temperature is decreased further. The effect is most pronounced in monolayer devices and cannot be understood in terms of known mechanisms. We propose a qualitative two-fluid vortex model in which thermal fluctuations of pinned vortices control the mobility of the free vortices. The findings provide a new perspective on fundamental questions of vortex mobility and dissipation in superconductors.
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Affiliation(s)
- Avishai Benyamini
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Dante M Kennes
- Institut für Theorie der Statistischen Physik, RWTH Aachen University and JARA-Fundamentals of Future Information Technology, 52056 Aachen, Germany
| | - Evan J Telford
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - 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
| | - Andrew J Millis
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
| | - Cory R Dean
- Department of Physics, Columbia University, New York, New York 10027, United States
| | - Abhay N Pasupathy
- Department of Physics, Columbia University, New York, New York 10027, United States
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15
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Ienaga K, Hayashi T, Tamoto Y, Kaneko S, Okuma S. Quantum Criticality inside the Anomalous Metallic State of a Disordered Superconducting Thin Film. PHYSICAL REVIEW LETTERS 2020; 125:257001. [PMID: 33416373 DOI: 10.1103/physrevlett.125.257001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 11/10/2020] [Indexed: 06/12/2023]
Abstract
The field-induced superconductor-insulator transition (SIT) in two-dimensional (2D) systems is a famous example of a quantum phase transition. However, an emergence of an anomalous metallic state induced by field has been a long-standing problem in 2D superconductors. While theories predicted that the emergence is attributed to strong phase fluctuations of the superconducting order parameter due to quantum fluctuations, usual resistance measurements have not probed them directly. Here, using Nernst effect measurements, we uncover superconducting fluctuations in the vicinity of the field-induced metallic state in an amorphous Mo_{x}Ge_{1-x} thin film. The field range where the vortex Nernst signals are detectable remains nonzero toward zero temperature, and it locates inside the metallic state defined by the magnetoresistance, indicating that the metallic state results from quantum vortex liquid (QVL) with phase fluctuations due to quantum fluctuations. Slow decay of transport entropy of vortices in the QVL with decreasing temperature suggests that the metallic state originates from broadening of a quantum critical point in SIT.
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Affiliation(s)
- K Ienaga
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan
| | - T Hayashi
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Y Tamoto
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan
| | - S Kaneko
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan
| | - S Okuma
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan
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16
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Conductivity Extraction Using a 180 GHz Quasi-Optical Resonator for Conductive Thin Film Deposited on Conductive Substrate. MATERIALS 2020; 13:ma13225260. [PMID: 33233851 PMCID: PMC7699854 DOI: 10.3390/ma13225260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/15/2020] [Accepted: 11/18/2020] [Indexed: 11/17/2022]
Abstract
Measurement of electrical conductivity of conductive thin film deposited on a conductive substrate is important and challenging. An effective conductivity model was constructed for a bilayer structure to extract thin film conductivity from the measured Q-factor of a quasi-optical resonator. As a demonstration, aluminium films with thickness of 100 nm were evaporated on four silicon wafers whose conductivity ranges from ~101 to ~105 S/m (thus, the proposed method can be verified for a substrate with a wide range of conductivity). Measurement results at ~180 GHz show that average conductivities are 1.66 × 107 S/m (which agrees well with direct current measurements) with 6% standard deviation. The proposed method provides a contactless conductivity evaluation method for conductive thin film deposited on conductive substrate which cannot be achieved by the existing microwave resonant method.
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17
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Abstract
The rise of two-dimensional (2D) crystalline superconductors has opened a new frontier of investigating unconventional quantum phenomena in low dimensions. However, despite the enormous advances achieved towards understanding the underlying physics, practical device applications like sensors and detectors using 2D superconductors are still lacking. Here, we demonstrate nonreciprocal antenna devices based on atomically thin NbSe2. Reversible nonreciprocal charge transport is unveiled in 2D NbSe2 through multi-reversal antisymmetric second harmonic magnetoresistance isotherms. Based on this nonreciprocity, our NbSe2 antenna devices exhibit a reversible nonreciprocal sensitivity to externally alternating current (AC) electromagnetic waves, which is attributed to the vortex flow in asymmetric pinning potentials driven by the AC driving force. More importantly, a successful control of the nonreciprocal sensitivity of the antenna devices has been achieved by applying electromagnetic waves with different frequencies and amplitudes. The device’s response increases with increasing electromagnetic wave amplitude and exhibits prominent broadband sensing from 5 to 900 MHz. Here, the authors observe reversible nonreciprocal charge transport in two-dimensional NbSe2, and demonstrate antenna devices exhibiting strong sensitivity to driving AC electromagnetic waves in the superconducting regime.
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18
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Zaytseva I, Abaloszew A, Camargo BC, Syryanyy Y, Cieplak MZ. Upper critical field and superconductor-metal transition in ultrathin niobium films. Sci Rep 2020; 10:19062. [PMID: 33149161 PMCID: PMC7642399 DOI: 10.1038/s41598-020-75968-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 10/20/2020] [Indexed: 11/09/2022] Open
Abstract
Recent studies suggest that in disordered ultrathin films superconducting (SC) state may be intrinsically inhomogeneous. Here we investigate the nature of SC state in ultrathin Nb films, of thickness d ranging from 1.2 to 20 nm, which undergo a transition from amorphous to polycrystalline structure at the thickness [Formula: see text] nm. We show that the properties of SC state are very different in polycrystalline and amorphous films. The upper critical field ([Formula: see text]) is orbitally limited in the first case, and paramagnetically limited in the latter. The magnetic field induced superconductor-metal transition is observed, with the critical field approximately constant or decreasing as a power-law with the film conductance in polycrystalline or amorphous films, respectively. The scaling analysis indicates distinct scaling exponents in these two types of films. Negative contribution of the SC fluctuations to conductivity exists above [Formula: see text], particularly pronounced in amorphous films, signaling the presence of fluctuating Cooper pairs. These observations suggest the development of local inhomogeneities in the amorphous films, in the form of proximity-coupled SC islands. An usual evolution of SC correlations on cooling is observed in amorphous films, likely related to the effect of quantum fluctuations on the proximity-induced phase coherence.
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Affiliation(s)
- Iryna Zaytseva
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02668, Warsaw, Poland.
| | - Aleksander Abaloszew
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02668, Warsaw, Poland
| | - Bruno C Camargo
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02668, Warsaw, Poland
| | - Yevgen Syryanyy
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02668, Warsaw, Poland
| | - Marta Z Cieplak
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02668, Warsaw, Poland.
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19
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Han X, Wu Y, Xiao H, Zhang M, Gao M, Liu Y, Wang J, Hu T, Xie X, Di Z. Disorder-Induced Quantum Griffiths Singularity Revealed in an Artificial 2D Superconducting System. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:1902849. [PMID: 33101841 PMCID: PMC7578859 DOI: 10.1002/advs.201902849] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 07/26/2020] [Indexed: 06/02/2023]
Abstract
Disorder-induced Griffiths singularity of quantum phase transition (QPT) is a crucial issue in 2D superconductors (2DSC). In a superconducting system, the strength of disorder is found to be associated with the vortex pinning energy, which is closely related to the quantum Griffiths singularity; however, a direct study to elucidate the role of vortex pinning energy on the quantum Griffiths singularity in 2DSC remains to be undertaken. Here, an artificial 2DSC system is designed by randomly depositing superconducting nanoislands on 2Delectron gas (2DEG). Quantum Griffiths singularity is present in a graphene/Pb-islands-array hybrid, where the superconducting behavior transits to weakly localized metallic behavior induced by the vertical magnetic field and exhibits critical behavior with a diverging dynamical critical exponent approaching zero temperature. Compared to the study of graphene/Sn-islands-array hybrid where the sharp QPT is observed, the vortex pinning energy acquired from the Arrhenius plot analysis is greater in graphene/Pb-islands-array hybrid, which may contribute to the presence of the quantum Griffiths singularity. This work may provide a comprehensive interpretation of the QPT in 2DSC.
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Affiliation(s)
- Xiaowen Han
- State Key Laboratory of Functional Materials for InformaticsShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of SciencesBeijing100049China
| | - Yufeng Wu
- State Key Laboratory of Functional Materials for InformaticsShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of SciencesBeijing100049China
- CAS Center for Excellence in Superconducting Electronics (CENSE)Shanghai200050China
| | - Hong Xiao
- Center for High Pressure Science and Technology Advanced ResearchBeijing100094China
| | - Miao Zhang
- State Key Laboratory of Functional Materials for InformaticsShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
| | - Min Gao
- State Key Laboratory of Functional Materials for InformaticsShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
- Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of SciencesBeijing100049China
| | - Yi Liu
- International Center for Quantum MaterialsSchool of PhysicsPeking UniversityBeijing100871China
- Collaborative Innovation Center of Quantum MatterBeijing100871China
| | - Jian Wang
- International Center for Quantum MaterialsSchool of PhysicsPeking UniversityBeijing100871China
- Collaborative Innovation Center of Quantum MatterBeijing100871China
- CAS Center for Excellence in Topological Quantum ComputationUniversity of Chinese Academy of SciencesBeijing100190China
- Beijing Academy of Quantum Information SciencesWest Bld. #3, No. 10 Xibeiwang East Rd., Haidian DistrictBeijing100193China
| | - Tao Hu
- State Key Laboratory of Functional Materials for InformaticsShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
- CAS Center for Excellence in Superconducting Electronics (CENSE)Shanghai200050China
- Beijing Academy of Quantum Information SciencesWest Bld. #3, No. 10 Xibeiwang East Rd., Haidian DistrictBeijing100193China
| | - Xiaoming Xie
- State Key Laboratory of Functional Materials for InformaticsShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
- CAS Center for Excellence in Superconducting Electronics (CENSE)Shanghai200050China
| | - Zengfeng Di
- State Key Laboratory of Functional Materials for InformaticsShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences865 Changning RoadShanghai200050China
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20
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Wu Y, Dutta S, Jesudasan J, Frydman A, Roy A. AC measurement of the Nernst effect of thin films at low temperatures. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:095112. [PMID: 33003765 DOI: 10.1063/5.0007653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 09/04/2020] [Indexed: 06/11/2023]
Abstract
We describe an alternating current method to measure the Nernst effect in superconducting thin films at low temperatures. The Nernst effect is an important tool in the understanding of superconducting fluctuations and, in particular, vortex motion near critical points. However, in most materials, the Nernst signal in a typical experimental setup rarely exceeds a few μV, in some cases being as low as a few nV. DC measurements of such small signals require extensive signal processing and protection against stray pickups and offsets, limiting the sensitivity of such measurements to >1 nV. Here, we describe a method utilizing a one-heater-two-thermometer setup with the heating element and thermometers fabricated on-chip with the sample, which helped to reduce the thermal load and temperature lag between the substrate and the thermometer. Using AC heating power and 2ω measurement, we are able to achieve sub-nanovolt sensitivity in 20 nm-30 nm thin superconducting films on a glass substrate, compared to a sensitivity of ∼10 nV using DC techniques on the same setup.
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Affiliation(s)
- Y Wu
- Department of Physics, Jack and Pearl Resnick Institute and the Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - S Dutta
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - J Jesudasan
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - A Frydman
- Department of Physics, Jack and Pearl Resnick Institute and the Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - A Roy
- Department of Physics, Jack and Pearl Resnick Institute and the Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
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21
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Liu Y, Xu Y, Sun J, Liu C, Liu Y, Wang C, Zhang Z, Gu K, Tang Y, Ding C, Liu H, Yao H, Lin X, Wang L, Xue QK, Wang J. Type-II Ising Superconductivity and Anomalous Metallic State in Macro-Size Ambient-Stable Ultrathin Crystalline Films. NANO LETTERS 2020; 20:5728-5734. [PMID: 32584045 DOI: 10.1021/acs.nanolett.0c01356] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recent emergence of two-dimensional (2D) crystalline superconductors has provided a promising platform to investigate novel quantum physics and potential applications. To reveal essential quantum phenomena therein, ultralow temperature transport investigation on high-quality ultrathin superconducting films is critically required, although it has been quite challenging experimentally. Here, we report a systematic transport study on the ultrathin crystalline PdTe2 films grown by molecular beam epitaxy (MBE). Interestingly, a new type of Ising superconductivity in 2D centrosymmetric materials is revealed by the detection of large in-plane critical field more than 7 times the Pauli limit. Remarkably, in a perpendicular magnetic field, we provide solid evidence of an anomalous metallic state characterized by the resistance saturation at low temperatures with high-quality filters. The robust superconductivity with intriguing quantum phenomena in the macro-size ambient-stable ultrathin PdTe2 films remains almost the same for 20 months, showing great potentials in electronic and spintronic applications.
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Affiliation(s)
- Yi Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Yong Xu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Jian Sun
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Chong Liu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yanzhao Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Chong Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
| | - Zetao Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Kaiyuan Gu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Yue Tang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Cui Ding
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Haiwen Liu
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Hong Yao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
| | - Xi Lin
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
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22
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Falson J, Xu Y, Liao M, Zang Y, Zhu K, Wang C, Zhang Z, Liu H, Duan W, He K, Liu H, Smet JH, Zhang D, Xue QK. Type-II Ising pairing in few-layer stanene. Science 2020; 367:1454-1457. [DOI: 10.1126/science.aax3873] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 02/27/2020] [Indexed: 01/14/2023]
Abstract
Spin-orbit coupling has proven indispensable in the realization of topological materials and, more recently, Ising pairing in two-dimensional superconductors. This pairing mechanism relies on inversion symmetry–breaking and sustains anomalously large in-plane polarizing magnetic fields whose upper limit is predicted to diverge at low temperatures. Here, we show that the recently discovered superconductor few-layer stanene, epitaxially strained gray tin (α-Sn), exhibits a distinct type of Ising pairing between carriers residing in bands with different orbital indices near the Γ-point. The bands are split as a result of spin-orbit locking without the participation of inversion symmetry–breaking. The in-plane upper critical field is strongly enhanced at ultralow temperature and reveals the predicted upturn.
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Affiliation(s)
- Joseph Falson
- Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Yong Xu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Frontier Science Center for Quantum Information, Beijing 100084, China
| | - Menghan Liao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yunyi Zang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Kejing Zhu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Chong Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zetao Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Hongchao Liu
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Wenhui Duan
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
| | - Ke He
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Haiwen Liu
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Jurgen H. Smet
- Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Ding Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
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23
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Superconducting phase transitions in disordered NbTiN films. Sci Rep 2020; 10:1471. [PMID: 32001735 PMCID: PMC6992621 DOI: 10.1038/s41598-020-58192-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 01/13/2020] [Indexed: 11/08/2022] Open
Abstract
Suppression of superconductivity in disordered systems is a fundamental problem of condensed matter physics. Here we investigate superconducting niobium-titanium-nitride (Nb1-xTixN) thin films grown by the atomic layer deposition (ALD) with slightly different growth process parameters. We observe a smooth crossover from the disorder-driven superconductor-normal metal transition (SMT) to the superconductor-insulator transition (SIT) via the intermediate Bose metal state detected by the low-temperature saturation of the temperature dependence of the sheet resistance. We demonstrate that the SIT via the intervening Bose metal state occurs if the sheet resistance of the film in the maximum, Rmax prior to the superconducting drop of R(T), exceeds Rq = h/4e2.
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24
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Yang C, Liu Y, Wang Y, Feng L, He Q, Sun J, Tang Y, Wu C, Xiong J, Zhang W, Lin X, Yao H, Liu H, Fernandes G, Xu J, Valles JM, Wang J, Li Y. Intermediate bosonic metallic state in the superconductor-insulator transition. Science 2019; 366:1505-1509. [DOI: 10.1126/science.aax5798] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 11/01/2019] [Indexed: 11/02/2022]
Abstract
Whether a metallic ground state exists in a two-dimensional system beyond Anderson localization remains an unresolved question. We studied how quantum phase coherence evolves across superconductor–metal–insulator transitions through magnetoconductance quantum oscillations in nanopatterned high-temperature superconducting films. We tuned the degree of phase coherence by varying the etching time of our films. Between the superconducting and insulating regimes, we detected a robust intervening anomalous metallic state characterized by saturating resistance and oscillation amplitude at low temperatures. Our measurements suggest that the anomalous metallic state is bosonic and that the saturation of phase coherence plays a prominent role in its formation.
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Affiliation(s)
- Chao Yang
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Yi Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Yang Wang
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Liu Feng
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Qianmei He
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Jian Sun
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Yue Tang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Chunchun Wu
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Jie Xiong
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Wanli Zhang
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Xi Lin
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Hong Yao
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
| | - Haiwen Liu
- Center for Advanced Quantum Studies, Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Gustavo Fernandes
- School of Engineering, Brown University, 182 Hope Street, Providence, RI 02912, USA
| | - Jimmy Xu
- School of Engineering, Brown University, 182 Hope Street, Providence, RI 02912, USA
- Department of Physics, Brown University, 182 Hope Street, Providence, RI 02912, USA
| | - James M. Valles
- Department of Physics, Brown University, 182 Hope Street, Providence, RI 02912, USA
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
| | - Yanrong Li
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
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25
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Li L, Chen C, Watanabe K, Taniguchi T, Zheng Y, Xu Z, Pereira VM, Loh KP, Castro Neto AH. Anomalous Quantum Metal in a 2D Crystalline Superconductor with Electronic Phase Nonuniformity. NANO LETTERS 2019; 19:4126-4133. [PMID: 31082262 DOI: 10.1021/acs.nanolett.9b01574] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The details of the superconducting to quantum metal transition (SQMT) at T = 0 are an open problem that invokes great interest in the nature of this exotic and unexpected ground state (Ephron et al., 1996; Mason and Kapitulnik, 1999; Chervenak and Valles, 2000). However, the SQMT was not yet investigated in a crystalline 2D superconductor with coexisting and fluctuating quantum orders. Here, we report the observation of a SQMT in 2D ion-gel-gated 1T-TiSe2 (Li et al., 2016) driven by a magnetic field. A field-induced crossover between Bose quantum metal and vortex quantum creeping with an increasing field is observed. We discuss the interplay between superconducting and CDW fluctuations (discommensurations) and their relation to the anomalous quantum metal (AQM) phase. From our findings, gate-tunable 1T-TiSe2 emerges as a privileged platform to scrutinize, in a controlled way, the details of the SQMT, the role of coexisting fluctuating orders and, ultimately, to obtain a deeper understanding of the fate of superconductivity in strictly two-dimensional crystals near zero temperature.
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Affiliation(s)
- Linjun Li
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering , Zhejiang University , Hangzhou 310027 , China
| | - Chuan Chen
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551
| | - 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
| | - Yi Zheng
- Department of Physics , Zhejiang University , Hangzhou 310027 , China
| | - Zhuan Xu
- Department of Physics , Zhejiang University , Hangzhou 310027 , China
| | - Vitor M Pereira
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551
| | - Kian Ping Loh
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
- Department of Chemistry , National University of Singapore , 3 Science Drive 3 , Singapore 117543
| | - Antonio H Castro Neto
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , Singapore 117546
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117551
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