1
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Henríquez-Guerra E, Almonte L, Li H, Elvira D, Calvo MR, Castellanos-Gomez A. Modulation of the Superconducting Phase Transition in Multilayer 2H-NbSe 2 Induced by Uniform Biaxial Compressive Strain. NANO LETTERS 2024; 24:10504-10509. [PMID: 39075987 PMCID: PMC11363131 DOI: 10.1021/acs.nanolett.4c02421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 07/24/2024] [Accepted: 07/24/2024] [Indexed: 07/31/2024]
Abstract
Strain is a powerful tool for tuning the properties of two-dimensional materials. Here, we investigated the effects of large, uniform biaxial compressive strain on the superconducting phase transition of multilayered 2H-NbSe2 flakes. We observed a consistent decrease in the critical temperature of NbSe2 flakes induced by the large thermal compression of a polymeric substrate (>1.2%) at cryogenic temperatures. For thin flakes (∼10 nm thick), a strong modulation of the critical temperature up to 1.5 K is observed, which monotonically decreases with increasing flake thickness. The effects of biaxial compressive strain remain significant even for relatively thick samples up to 80 nm thick, indicating efficient transfer of strain not only from the substrate to the flakes but also across several van der Waals layers. This work demonstrates that compressive strain induced from substrate thermal deformation can effectively tune phase transitions at low temperatures in 2D materials.
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Affiliation(s)
- Eudomar Henríquez-Guerra
- Departamento
de Física Aplicada, Universidad de
Alicante, 03690 Alicante, Spain
- Instituto
Universitario de Materiales IUMA, Universidad
de Alicante, 03690 Alicante, Spain
- BCMaterials,
Basque Center for Materials, Applications and Nanostructures, 48940 Leioa, Spain
| | - Lisa Almonte
- Departamento
de Física Aplicada, Universidad de
Alicante, 03690 Alicante, Spain
- Instituto
Universitario de Materiales IUMA, Universidad
de Alicante, 03690 Alicante, Spain
- BCMaterials,
Basque Center for Materials, Applications and Nanostructures, 48940 Leioa, Spain
| | - Hao Li
- 2D
Foundry Group, Instituto de Ciencia de Materiales
de Madrid, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain
| | - Daniel Elvira
- Departamento
de Física Aplicada, Universidad de
Alicante, 03690 Alicante, Spain
- Instituto
Universitario de Materiales IUMA, Universidad
de Alicante, 03690 Alicante, Spain
| | - M. Reyes Calvo
- Departamento
de Física Aplicada, Universidad de
Alicante, 03690 Alicante, Spain
- Instituto
Universitario de Materiales IUMA, Universidad
de Alicante, 03690 Alicante, Spain
- BCMaterials,
Basque Center for Materials, Applications and Nanostructures, 48940 Leioa, Spain
- IKERBASQUE,
Basque Foundation for Science, Plaza Euskadi 5, 48009 Bilbao, Spain
| | - Andres Castellanos-Gomez
- 2D
Foundry Group, Instituto de Ciencia de Materiales
de Madrid, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain
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2
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Abstract
Abstract
Ionic gating is a very popular tool to investigate and control the electric charge transport and electronic ground state in a wide variety of different materials. This is due to its capability to induce large modulations of the surface charge density by means of the electric-double-layer field-effect transistor (EDL-FET) architecture, and has been proven to be capable of tuning even the properties of metallic systems. In this short review, I summarize the main results which have been achieved so far in controlling the superconducting (SC) properties of thin films of conventional metallic superconductors by means of the ionic gating technique. I discuss how the gate-induced charge doping, despite being confined to a thin surface layer by electrostatic screening, results in a long-range ‘bulk’ modulation of the SC properties by the coherent nature of the SC condensate, as evidenced by the observation of suppressions in the critical temperature of films much thicker than the electrostatic screening length, and by the pronounced thickness-dependence of their magnitude. I review how this behavior can be modelled in terms of proximity effect between the charge-doped surface layer and the unperturbed bulk with different degrees of approximation, and how first-principles calculations have been employed to determine the origin of an anomalous increase in the electrostatic screening length at ultrahigh electric fields, thus fully confirming the validity of the proximity effect model. Finally, I discuss a general framework—based on the combination of ab-initio Density Functional Theory and the Migdal-Eliashberg theory of superconductivity—by which the properties of any gated thin film of a conventional metallic superconductor can be determined purely from first principles.
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3
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Fatemi V, Wu S, Cao Y, Bretheau L, Gibson QD, Watanabe K, Taniguchi T, Cava RJ, Jarillo-Herrero P. Electrically tunable low-density superconductivity in a monolayer topological insulator. Science 2018; 362:926-929. [DOI: 10.1126/science.aar4642] [Citation(s) in RCA: 204] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 10/09/2018] [Indexed: 01/14/2023]
Affiliation(s)
- Valla Fatemi
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sanfeng Wu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yuan Cao
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Landry Bretheau
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA, 91128 Palaiseau Cedex, France
| | - Quinn D. Gibson
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZX, UK
| | - Kenji Watanabe
- Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Robert J. Cava
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Pablo Jarillo-Herrero
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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4
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Roy A, Shimshoni E, Frydman A. Quantum Criticality at the Superconductor-Insulator Transition Probed by the Nernst Effect. PHYSICAL REVIEW LETTERS 2018; 121:047003. [PMID: 30095933 DOI: 10.1103/physrevlett.121.047003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Indexed: 06/08/2023]
Abstract
The superconductor-insulator transition (SIT) is an excellent example of a quantum phase transition at zero temperature, dominated by quantum fluctuations. These are expected to be very prominent close to the quantum critical point. So far, most of the experimental studies of the SIT have concentrated on transport properties and tunneling experiments that provide indirect information on criticality close to the transition. Here we present an experiment uniquely designed to study the evolution of quantum fluctuations through the quantum critical point. We utilize the Nernst effect, which has been shown to be effective in probing superconducting fluctuation. We measure the Nernst coefficient in amorphous indium oxide films tuned through the SIT and find a large signal on both the superconducting and the insulating sides, which peaks close to the critical point. The transverse Peltier coefficient α_{xy}, which is the thermodynamic quantity extracted from these measurements, follows quantum critical scaling with critical exponents ν∼0.7 and z∼1. These exponents are consistent with a clean X-Y model in 2+1 dimensions.
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Affiliation(s)
- A Roy
- Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel
| | - E Shimshoni
- Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel
| | - A Frydman
- Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel
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5
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Chen Q, Lu J, Liang L, Zheliuk O, Ali El Yumin A, Ye J. Continuous Low-Bias Switching of Superconductivity in a MoS 2 Transistor. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1800399. [PMID: 29806236 DOI: 10.1002/adma.201800399] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/09/2018] [Indexed: 06/08/2023]
Abstract
Engineering the properties of quantum electron systems, e.g., tuning the superconducting phase using low driving bias within an easily accessible temperature range, is of great interest for exploring exotic physical phenomena as well as achieving real applications. Here, the realization of continuous field-effect switching between superconducting and non-superconducting states in a few-layer MoS2 transistor is reported. Ionic-liquid gating induces the superconducting state close to the quantum critical point on the top surface of the MoS2 , and continuous switching between the super/non-superconducting states is achieved by HfO2 back gating. The superconducting transistor works effectively in the helium-4 temperature range and requires a gate bias as low as ≈10 V. The dual-gate device structure and strategy presented here can be easily generalized to other systems, opening new opportunities for designing high-performance 2D superconducting transistors.
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Affiliation(s)
- Qihong Chen
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, 9747, AG, The Netherlands
| | - Jianming Lu
- State Key Laboratory for Mesoscopic Physics, Peking University, Beijing, 100871, P. R. China
| | - Lei Liang
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, 9747, AG, The Netherlands
| | - Oleksandr Zheliuk
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, 9747, AG, The Netherlands
| | - Abdurrahman Ali El Yumin
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, 9747, AG, The Netherlands
| | - Jianting Ye
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, 9747, AG, The Netherlands
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6
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Doron A, Tamir I, Levinson T, Ovadia M, Sacépé B, Shahar D. Instability of Insulators near Quantum Phase Transitions. PHYSICAL REVIEW LETTERS 2017; 119:247001. [PMID: 29286730 DOI: 10.1103/physrevlett.119.247001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Indexed: 06/07/2023]
Abstract
Thin films of amorphous indium oxide undergo a magnetic field driven superconducting to insulator quantum phase transition. In the insulating phase, the current-voltage characteristics show large current discontinuities due to overheating of electrons. We show that the onset voltage for the discontinuities vanishes as we approach the quantum critical point. As a result, the insulating phase becomes unstable with respect to any applied voltage making it, at least experimentally, immeasurable. We emphasize that unlike previous reports of the absence of linear response near quantum phase transitions, in our system, the departure from equilibrium is discontinuous. Because the conditions for these discontinuities are satisfied in most insulators at low temperatures, and due to the decay of all characteristic energy scales near quantum phase transitions, we believe that this instability is general and should occur in various systems while approaching their quantum critical point. Accounting for this instability is crucial for determining the critical behavior of systems near the transition.
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Affiliation(s)
- A Doron
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - I Tamir
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - T Levinson
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - M Ovadia
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - B Sacépé
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - D Shahar
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
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7
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Sterpetti E, Biscaras J, Erb A, Shukla A. Comprehensive phase diagram of two-dimensional space charge doped Bi 2Sr 2CaCu 2O 8+x. Nat Commun 2017; 8:2060. [PMID: 29233988 PMCID: PMC5727194 DOI: 10.1038/s41467-017-02104-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 11/07/2017] [Indexed: 11/09/2022] Open
Abstract
The phase diagram of hole-doped high critical temperature superconductors as a function of doping and temperature has been intensively studied with chemical variation of doping. Chemical doping can provoke structural changes and disorder, masking intrinsic effects. Alternatively, a field-effect transistor geometry with an electrostatically doped, ultra-thin sample can be used. However, to probe the phase diagram, carrier density modulation beyond 1014 cm−2 and transport measurements performed over a large temperature range are needed. Here we use the space charge doping method to measure transport characteristics from 330 K to low temperature. We extract parameters and characteristic temperatures over a large doping range and establish a comprehensive phase diagram for one-unit-cell-thick BSCCO-2212 as a function of doping, temperature and disorder. The determination of the phase diagram of cuprate superconductors involves chemical doping which introduces disorder and could mask intrinsic effects. Sterpetti et al. establish this phase diagram with transport measurements in ultra-thin samples by modulating the carrier density with an alternative electrostatic method.
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Affiliation(s)
- Edoardo Sterpetti
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Universités, Université Pierre et Marie Curie Paris 6, UMR CNRS 7590, MNHN, IRD UMR 206, 4 Place Jussieu, F-75005, Paris, France
| | - Johan Biscaras
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Universités, Université Pierre et Marie Curie Paris 6, UMR CNRS 7590, MNHN, IRD UMR 206, 4 Place Jussieu, F-75005, Paris, France
| | - Andreas Erb
- Walther Meissner Institut fur Tieftemperaturforschung, Bayerische Akademie der Wissenschaften, Walther-Meissnerstr. 8, 85748, Garching, Germany
| | - Abhay Shukla
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Universités, Université Pierre et Marie Curie Paris 6, UMR CNRS 7590, MNHN, IRD UMR 206, 4 Place Jussieu, F-75005, Paris, France.
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8
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Bisri SZ, Shimizu S, Nakano M, Iwasa Y. Endeavor of Iontronics: From Fundamentals to Applications of Ion-Controlled Electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1607054. [PMID: 28582588 DOI: 10.1002/adma.201607054] [Citation(s) in RCA: 185] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 02/16/2017] [Indexed: 05/28/2023]
Abstract
Iontronics is a newly emerging interdisciplinary concept which bridges electronics and ionics, covering electrochemistry, solid-state physics, electronic engineering, and biological sciences. The recent developments of electronic devices are highlighted, based on electric double layers formed at the interface between ionic conductors (but electronically insulators) and various electronic conductors including organics and inorganics (oxides, chalcogenide, and carbon-based materials). Particular attention is devoted to electric-double-layer transistors (EDLTs), which are producing a significant impact, particularly in electrical control of phase transitions, including superconductivity, which has been difficult or impossible in conventional all-solid-state electronic devices. Besides that, the current state of the art and the future challenges of iontronics are also reviewed for many applications, including flexible electronics, healthcare-related devices, and energy harvesting.
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Affiliation(s)
- Satria Zulkarnaen Bisri
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Sunao Shimizu
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Masaki Nakano
- Quantum Phase Electronic Center (QPEC) and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Yoshihiro Iwasa
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- Quantum Phase Electronic Center (QPEC) and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
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9
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Poran S, Nguyen-Duc T, Auerbach A, Dupuis N, Frydman A, Bourgeois O. Quantum criticality at the superconductor-insulator transition revealed by specific heat measurements. Nat Commun 2017; 8:14464. [PMID: 28224994 PMCID: PMC5322500 DOI: 10.1038/ncomms14464] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 01/03/2017] [Indexed: 11/09/2022] Open
Abstract
The superconductor–insulator transition (SIT) is considered an excellent example of a quantum phase transition that is driven by quantum fluctuations at zero temperature. The quantum critical point is characterized by a diverging correlation length and a vanishing energy scale. Low-energy fluctuations near quantum criticality may be experimentally detected by specific heat, cp, measurements. Here we use a unique highly sensitive experiment to measure cp of two-dimensional granular Pb films through the SIT. The specific heat shows the usual jump at the mean field superconducting transition temperature marking the onset of Cooper pairs formation. As the film thickness is tuned towards the SIT, is relatively unchanged, while the magnitude of the jump and low-temperature specific heat increase significantly. This behaviour is taken as the thermodynamic fingerprint of quantum criticality in the vicinity of a quantum phase transition. To detect thermodynamic signatures of quantum fluctuations for quantum phase transitions is challenging. Here, Poran et al. report a significant increase in the specific heat when the thickness of granular Pb films approaches a superconductor-insulator transition.
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Affiliation(s)
- S Poran
- Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel.,Institut NÉEL, CNRS, 25 avenue des Martyrs, F-38042 Grenoble, France
| | - T Nguyen-Duc
- Institut NÉEL, CNRS, 25 avenue des Martyrs, F-38042 Grenoble, France.,Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France
| | - A Auerbach
- Department of Physics, Technion, 32000 Haifa, Israel.,Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR 7600, UPMC-Sorbonne Universités, 4 Place Jussieu, 75252 Paris, France
| | - N Dupuis
- Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR 7600, UPMC-Sorbonne Universités, 4 Place Jussieu, 75252 Paris, France
| | - A Frydman
- Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel.,Institut NÉEL, CNRS, 25 avenue des Martyrs, F-38042 Grenoble, France.,Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France
| | - Olivier Bourgeois
- Institut NÉEL, CNRS, 25 avenue des Martyrs, F-38042 Grenoble, France.,Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France
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10
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In operando evidence of deoxygenation in ionic liquid gating of YBa2Cu3O7-X. Proc Natl Acad Sci U S A 2016; 114:215-220. [PMID: 28028236 DOI: 10.1073/pnas.1613006114] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Field-effect experiments on cuprates using ionic liquids have enabled the exploration of their rich phase diagrams [Leng X, et al. (2011) Phys Rev Lett 107(2):027001]. Conventional understanding of the electrostatic doping is in terms of modifications of the charge density to screen the electric field generated at the double layer. However, it has been recently reported that the suppression of the metal to insulator transition induced in VO2 by ionic liquid gating is due to oxygen vacancy formation rather than to electrostatic doping [Jeong J, et al. (2013) Science 339(6126):1402-1405]. These results underscore the debate on the true nature, electrostatic vs. electrochemical, of the doping of cuprates with ionic liquids. Here, we address the doping mechanism of the high-temperature superconductor YBa2Cu3O7-X (YBCO) by simultaneous ionic liquid gating and X-ray absorption experiments. Pronounced spectral changes are observed at the Cu K-edge concomitant with the superconductor-to-insulator transition, evidencing modification of the Cu coordination resulting from the deoxygenation of the CuO chains, as confirmed by first-principles density functional theory (DFT) simulations. Beyond providing evidence of the importance of chemical doping in electric double-layer (EDL) gating experiments with superconducting cuprates, our work shows that interfacing correlated oxides with ionic liquids enables a delicate control of oxygen content, paving the way to novel electrochemical concepts in future oxide electronics.
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11
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Ma HJH, Scharinger S, Zeng SW, Kohlberger D, Lange M, Stöhr A, Wang XR, Venkatesan T, Kleiner R, Scott JF, Coey JMD, Koelle D. Local Electrical Imaging of Tetragonal Domains and Field-Induced Ferroelectric Twin Walls in Conducting SrTiO_{3}. PHYSICAL REVIEW LETTERS 2016; 116:257601. [PMID: 27391752 DOI: 10.1103/physrevlett.116.257601] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Indexed: 06/06/2023]
Abstract
We demonstrate electrical mapping of tetragonal domains and electric field-induced twin walls in SrTiO_{3} as a function of temperature and gate bias utilizing the conducting LaAlO_{3}/SrTiO_{3} interface and low-temperature scanning electron microscopy. Conducting twin walls appear below 105 K, and new twin patterns are observed after thermal cycling through the transition or on electric field gating. The nature of the twin walls is confirmed by calculating their intersection angles for different substrate orientations. Numerous walls formed when a large side- or back-gate voltage is applied are identified as field-induced ferroelectric twin walls in the paraelectric tetragonal matrix. The walls persist after switching off the electric field and on thermal cycling below 105 K. These observations point to a new type of ferroelectric functionality in SrTiO_{3}, which could be exploited together with magnetism and superconductivity in a multifunctional context.
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Affiliation(s)
- H J Harsan Ma
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore, Singapore
- Department of Physics, National University of Singapore, 117542 Singapore, Singapore
| | - S Scharinger
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - S W Zeng
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore, Singapore
- Department of Physics, National University of Singapore, 117542 Singapore, Singapore
| | - D Kohlberger
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - M Lange
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - A Stöhr
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - X Renshaw Wang
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore, Singapore
- Department of Physics, National University of Singapore, 117542 Singapore, Singapore
| | - T Venkatesan
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore, Singapore
- Department of Physics, National University of Singapore, 117542 Singapore, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, 117576 Singapore, Singapore
| | - R Kleiner
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - J F Scott
- School of Chemistry and School of Physics, St. Andrews University, St. Andrews KY16 9ST, United Kingdom
| | - J M D Coey
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore, Singapore
- Department of Pure and Applied Physics, Trinity College, Dublin 2, Ireland
| | - D Koelle
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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12
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Doron A, Tamir I, Mitra S, Zeltzer G, Ovadia M, Shahar D. Nonequilibrium Second-Order Phase Transition in a Cooper-Pair Insulator. PHYSICAL REVIEW LETTERS 2016; 116:057001. [PMID: 26894728 DOI: 10.1103/physrevlett.116.057001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Indexed: 06/05/2023]
Abstract
In certain disordered superconductors, upon increasing the magnetic field, superconductivity terminates with a direct transition into an insulating phase. This phase is comprised of localized Cooper pairs and is termed a Cooper-pair insulator. The current-voltage characteristics measured in this insulating phase are highly nonlinear and, at low temperatures, exhibit abrupt current jumps. Increasing the temperature diminishes the jumps until the current-voltage characteristics become continuous. We show that a direct correspondence exists between our system and systems that undergo an equilibrium, second-order, phase transition. We illustrate this correspondence by comparing our results to the van der Waals equation of state for the liquid-gas mixture. We use the similarities to identify a critical point where an out of equilibrium second-order-like phase transition occurs in our system. Approaching the critical point, we find a power-law behavior with critical exponents that characterizes the transition.
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Affiliation(s)
- A Doron
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - I Tamir
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - S Mitra
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - G Zeltzer
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - M Ovadia
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - D Shahar
- Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
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13
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Controlling many-body states by the electric-field effect in a two-dimensional material. Nature 2015; 529:185-9. [PMID: 26700810 DOI: 10.1038/nature16175] [Citation(s) in RCA: 165] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Accepted: 10/19/2015] [Indexed: 12/23/2022]
Abstract
To understand the complex physics of a system with strong electron-electron interactions, the ideal is to control and monitor its properties while tuning an external electric field applied to the system (the electric-field effect). Indeed, complete electric-field control of many-body states in strongly correlated electron systems is fundamental to the next generation of condensed matter research and devices. However, the material must be thin enough to avoid shielding of the electric field in the bulk material. Two-dimensional materials do not experience electrical screening, and their charge-carrier density can be controlled by gating. Octahedral titanium diselenide (1T-TiSe2) is a prototypical two-dimensional material that reveals a charge-density wave (CDW) and superconductivity in its phase diagram, presenting several similarities with other layered systems such as copper oxides, iron pnictides, and crystals of rare-earth elements and actinide atoms. By studying 1T-TiSe2 single crystals with thicknesses of 10 nanometres or less, encapsulated in two-dimensional layers of hexagonal boron nitride, we achieve unprecedented control over the CDW transition temperature (tuned from 170 kelvin to 40 kelvin), and over the superconductivity transition temperature (tuned from a quantum critical point at 0 kelvin up to 3 kelvin). Electrically driving TiSe2 over different ordered electronic phases allows us to study the details of the phase transitions between many-body states. Observations of periodic oscillations of magnetoresistance induced by the Little-Parks effect show that the appearance of superconductivity is directly correlated with the spatial texturing of the amplitude and phase of the superconductivity order parameter, corresponding to a two-dimensional matrix of superconductivity. We infer that this superconductivity matrix is supported by a matrix of incommensurate CDW states embedded in the commensurate CDW states. Our results show that spatially modulated electronic states are fundamental to the appearance of two-dimensional superconductivity.
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Abstract
In superconductors the zero-resistance current-flow is protected from dissipation at finite temperatures (T) by virtue of the short-circuit condition maintained by the electrons that remain in the condensed state. The recently suggested finite-T insulator and the “superinsulating” phase are different because any residual mechanism of conduction will eventually become dominant as the finite-T insulator sets-in. If the residual conduction is small it may be possible to observe the transition to these intriguing states. We show that the conductivity of the high magnetic-field insulator terminating superconductivity in amorphous indium-oxide exhibits an abrupt drop, and seem to approach a zero conductance at T < 0.04 K. We discuss our results in the light of theories that lead to a finite-T insulator.
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15
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Continuous and reversible tuning of the disorder-driven superconductor-insulator transition in bilayer graphene. Sci Rep 2015; 5:13466. [PMID: 26310774 PMCID: PMC4550864 DOI: 10.1038/srep13466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 07/28/2015] [Indexed: 11/24/2022] Open
Abstract
The influence of static disorder on a quantum phase transition (QPT) is a fundamental issue in condensed matter physics. As a prototypical example of a disorder-tuned QPT, the superconductor–insulator transition (SIT) has been investigated intensively over the past three decades, but as yet without a general consensus on its nature. A key element is good control of disorder. Here, we present an experimental study of the SIT based on precise in-situ tuning of disorder in dual-gated bilayer graphene proximity-coupled to two superconducting electrodes through electrical and reversible control of the band gap and the charge carrier density. In the presence of a static disorder potential, Andreev-paired carriers formed close to the Fermi level in bilayer graphene constitute a randomly distributed network of proximity-induced superconducting puddles. The landscape of the network was easily tuned by electrical gating to induce percolative clusters at the onset of superconductivity. This is evidenced by scaling behavior consistent with the classical percolation in transport measurements. At lower temperatures, the solely electrical tuning of the disorder-induced landscape enables us to observe, for the first time, a crossover from classical to quantum percolation in a single device, which elucidates how thermal dephasing engages in separating the two regimes.
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Yu Y, Yang F, Lu XF, Yan YJ, Cho YH, Ma L, Niu X, Kim S, Son YW, Feng D, Li S, Cheong SW, Chen XH, Zhang Y. Gate-tunable phase transitions in thin flakes of 1T-TaS2. NATURE NANOTECHNOLOGY 2015; 10:270-276. [PMID: 25622230 DOI: 10.1038/nnano.2014.323] [Citation(s) in RCA: 291] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Accepted: 12/10/2014] [Indexed: 06/04/2023]
Abstract
The ability to tune material properties using gating by electric fields is at the heart of modern electronic technology. It is also a driving force behind recent advances in two-dimensional systems, such as the observation of gate electric-field-induced superconductivity and metal-insulator transitions. Here, we describe an ionic field-effect transistor (termed an iFET), in which gate-controlled Li ion intercalation modulates the material properties of layered crystals of 1T-TaS2. The strong charge doping induced by the tunable ion intercalation alters the energetics of various charge-ordered states in 1T-TaS2 and produces a series of phase transitions in thin-flake samples with reduced dimensionality. We find that the charge-density wave states in 1T-TaS2 collapse in the two-dimensional limit at critical thicknesses. Meanwhile, at low temperatures, the ionic gating induces multiple phase transitions from Mott-insulator to metal in 1T-TaS2 thin flakes, with five orders of magnitude modulation in resistance, and superconductivity emerges in a textured charge-density wave state induced by ionic gating. Our method of gate-controlled intercalation opens up possibilities in searching for novel states of matter in the extreme charge-carrier-concentration limit.
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Affiliation(s)
- Yijun Yu
- 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China
| | - Fangyuan Yang
- 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China
| | - Xiu Fang Lu
- 1] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China [2] Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China [3] Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ya Jun Yan
- 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China [3] Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yong-Heum Cho
- Laboratory for Pohang Emergent Materials and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Liguo Ma
- 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China
| | - Xiaohai Niu
- 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China
| | - Sejoong Kim
- Korea Institute for Advanced Study, Hoegiro 87, Dongdaemun-gu, Seoul, Korea
| | - Young-Woo Son
- Korea Institute for Advanced Study, Hoegiro 87, Dongdaemun-gu, Seoul, Korea
| | - Donglai Feng
- 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China
| | - Shiyan Li
- 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China
| | - Sang-Wook Cheong
- 1] Laboratory for Pohang Emergent Materials and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea [2] Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Xian Hui Chen
- 1] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China [2] Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China [3] Key Laboratory of Strongly Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yuanbo Zhang
- 1] State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China [2] Collaborative Innovation Center of Advanced Microstructures, 22 Hankou Road, Gulou, Nanjing 210093, China
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17
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Ghosh S, De Munshi D. The phenomenon of voltage controlled switching in disordered superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:025704. [PMID: 24318974 DOI: 10.1088/0953-8984/26/2/025704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The superconductor-to-insulator transition (SIT) is a phenomenon occurring in highly disordered superconductors and may be useful in the development of superconducting switches. The SIT has been demonstrated to be induced by different external parameters: temperature, magnetic field, electric field, etc. However, the electric field induced SIT (ESIT), which has been experimentally demonstrated for some specific materials, holds particular promise for practical device development. Here, we demonstrate, from theoretical considerations, the occurrence of the ESIT. We also propose a general switching device architecture using the ESIT and study some of its universal behavior, such as the effects of sample size, disorder strength and temperature on the switching action. This work provides a general framework for the development of such a device.
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Affiliation(s)
- Sanjib Ghosh
- Center for Quantum Technologies, National University of Singapore, 117543, Singapore
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18
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Ghosh S, Mandal SS. Amplitude fluctuations driven by the density of electron pairs within nanosize granular structures inside strongly disordered superconductors: evidence for a shell-like effect. PHYSICAL REVIEW LETTERS 2013; 111:207004. [PMID: 24289705 DOI: 10.1103/physrevlett.111.207004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Indexed: 06/02/2023]
Abstract
Motivated by the recent observation of the shell effect in a nanoscale pure superconductor by Bose et al. [Nat. Mater. 9, 550 (2010)], we explore the possible shell-like effect in a strongly disordered superconductor as it is known to produce nanosize superconducting puddles (SPs). We find a remarkable change in the texture of the pairing amplitudes that is responsible for forming the SP, upon monotonic tuning of the average electron density, <n>, and keeping the disorder landscape unaltered. Both the spatially averaged pairing amplitude and the quasiparticle excitation gap oscillate with <n>. This oscillation is due to a rapid change in the low-lying quasiparticle energy spectra and thereby a change in the shapes and positions of the SPs. We establish a correlation between the formation of SPs and the shell-like effect. The experimental consequences of our theory are also discussed.
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Affiliation(s)
- Sanjib Ghosh
- Department of Theoretical Physics, Indian Association for the Cultivation of Science, Kolkata 700 032, India
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19
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Liu TJ, Prestigiacomo JC, Adams PW. Electrostatic tuning of the proximity-induced exchange field in EuS/Al bilayers. PHYSICAL REVIEW LETTERS 2013; 111:027207. [PMID: 23889439 DOI: 10.1103/physrevlett.111.027207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 05/01/2013] [Indexed: 06/02/2023]
Abstract
We demonstrate that the proximity-induced exchange field H(ex) in ferromagnetic-paramagnetic bilayers can be modulated with an electric field. An electrostatic gate arrangement is used to tune the magnitude of H(ex) in the Al component of EuS/Al bilayers. In samples with H(ex)~2 T, we were able to produce modulations of ±10 mT with the application of perpendicular electric fields of the order of ±10(6) V/cm. We discuss several possible mechanisms accounting for the electric field's influence on the interfacial coupling between the Al layer and the ferromagnetic insulator EuS, along with the prospects of producing a superconducting field-effect transistor.
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Affiliation(s)
- T J Liu
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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20
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Vaz CAF. Electric field control of magnetism in multiferroic heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:333201. [PMID: 22824827 DOI: 10.1088/0953-8984/24/33/333201] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We review the recent developments in the electric field control of magnetism in multiferroic heterostructures, which consist of heterogeneous materials systems where a magnetoelectric coupling is engineered between magnetic and ferroelectric components. The magnetoelectric coupling in these composite systems is interfacial in origin, and can arise from elastic strain, charge, and exchange bias interactions, with different characteristic responses and functionalities. Moreover, charge transport phenomena in multiferroic heterostructures, where both magnetic and ferroelectric order parameters are used to control charge transport, suggest new possibilities to control the conduction paths of the electron spin, with potential for device applications.
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Affiliation(s)
- C A F Vaz
- SwissFEL, Paul Scherrer Institut, Villigen PSI, Switzerland.
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21
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Schneider R, Zaitsev AG, Fuchs D, V Löhneysen H. Superconductor-insulator quantum phase transition in disordered FeSe thin films. PHYSICAL REVIEW LETTERS 2012; 108:257003. [PMID: 23004643 DOI: 10.1103/physrevlett.108.257003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Indexed: 06/01/2023]
Abstract
The evolution of two-dimensional electronic transport with increasing disorder in epitaxial FeSe thin films is studied. Disorder is generated by reducing the film thickness. The extreme sensitivity of the films to disorder results in a superconductor-insulator transition. The finite-size scaling analysis in the critical regime based on the Bose-glass model strongly supports the idea of a continuous quantum phase transition. The obtained value for the critical-exponent product of approximately 7/3 suggests that the transition is governed by quantum percolation. Finite-size scaling with the same critical-exponent product is also substantiated when the superconductor-insulator transition is tuned with an applied magnetic field.
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Affiliation(s)
- R Schneider
- Institut für Festkörperphysik, Karlsruher Institut für Technologie, D-76021 Karlsruhe, Germany.
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22
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Allain A, Han Z, Bouchiat V. Electrical control of the superconducting-to-insulating transition in graphene-metal hybrids. NATURE MATERIALS 2012; 11:590-4. [PMID: 22609559 DOI: 10.1038/nmat3335] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 04/17/2012] [Indexed: 05/13/2023]
Abstract
Graphene is a sturdy and chemically inert material exhibiting an exposed two-dimensional electron gas of high mobility. These combined properties enable the design of graphene composites, based either on covalent or non-covalent coupling of adsorbates, or on stacked and multilayered heterostructures. These systems have shown tunable electronic properties such as bandgap engineering, reversible metal-insulating transition or supramolecular spintronics. Tunable superconductivity is expected as well, but experimental realization is lacking. Here, we show experiments based on metal-graphene hybrid composites, enabling the tunable proximity coupling of an array of superconducting nanoparticles of tin onto a macroscopic graphene sheet. This material allows full electrical control of the superconductivity down to a strongly insulating state at low temperature. The observed gate control of superconductivity results from the combination of a proximity-induced superconductivity generated by the metallic nanoparticle array with the two-dimensional and tunable metallicity of graphene. The resulting hybrid material behaves, as a whole, like a granular superconductor showing universal transition threshold and localization of Cooper pairs in the insulating phase. This experiment sheds light on the emergence of superconductivity in inhomogeneous superconductors, and more generally, it demonstrates the potential of graphene as a versatile building block for the realization of superconducting materials.
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Affiliation(s)
- Adrien Allain
- Institut Néel, CNRS-UJF-INP, BP 166, 38042 Grenoble cedex 9, France
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23
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Leng X, Garcia-Barriocanal J, Bose S, Lee Y, Goldman AM. Electrostatic control of the evolution from a superconducting phase to an insulating phase in ultrathin YBa₂Cu₃O(7-x) films. PHYSICAL REVIEW LETTERS 2011; 107:027001. [PMID: 21797633 DOI: 10.1103/physrevlett.107.027001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Indexed: 05/31/2023]
Abstract
The electrical transport properties of ultrathin YBa₂Cu₃O(7-x) films have been modified using an electric double layer transistor configuration employing an ionic liquid. A clear evolution from superconductor to insulator was observed in nominally 7 unit-cell-thick films. Using a finite size scaling analysis, curves of resistance versus temperature, R(T), over the temperature range from 6 to 22 K were found to collapse onto a single scaling function, which suggests the presence of a quantum critical point. However, the scaling fails at the lowest temperatures indicating the possible presence of an additional phase between the superconducting and insulating regimes.
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Affiliation(s)
- Xiang Leng
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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24
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Ueno K, Nakamura S, Shimotani H, Yuan HT, Kimura N, Nojima T, Aoki H, Iwasa Y, Kawasaki M. Discovery of superconductivity in KTaO₃ by electrostatic carrier doping. NATURE NANOTECHNOLOGY 2011; 6:408-412. [PMID: 21602813 DOI: 10.1038/nnano.2011.78] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 04/15/2011] [Indexed: 05/30/2023]
Abstract
Superconductivity at interfaces has been investigated since the first demonstration of electric-field-tunable superconductivity in ultrathin films in 1960(1). So far, research on interface superconductivity has focused on materials that are known to be superconductors in bulk. Here, we show that electrostatic carrier doping can induce superconductivity in KTaO(3), a material in which superconductivity has not been observed before. Taking advantage of the large capacitance of the self-organized electric double layer that forms at the interface between an ionic liquid and KTaO(3) (ref. 12), we achieve a charge carrier density that is an order of magnitude larger than the density that can be achieved with conventional chemical doping. Superconductivity emerges in KTaO(3) at 50 mK for two-dimensional carrier densities in the range 2.3 × 10(14) to 3.7 × 10(14) cm(-2). The present result clearly shows that electrostatic carrier doping can lead to new states of matter at nanoscale interfaces.
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Affiliation(s)
- K Ueno
- WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
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25
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Bollinger AT, Dubuis G, Yoon J, Pavuna D, Misewich J, Božović I. Superconductor–insulator transition in La2 − xSr x CuO4 at the pair quantum resistance. Nature 2011; 472:458-60. [DOI: 10.1038/nature09998] [Citation(s) in RCA: 393] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 03/11/2011] [Indexed: 11/09/2022]
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26
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Vaz CAF, Hoffman J, Ahn CH, Ramesh R. Magnetoelectric coupling effects in multiferroic complex oxide composite structures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:2900-18. [PMID: 20414887 DOI: 10.1002/adma.200904326] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The study of magnetoelectric materials has recently received renewed interest, in large part stimulated by breakthroughs in the controlled growth of complex materials and by the search for novel materials with functionalities suitable for next generation electronic devices. In this Progress Report, we present an overview of recent developments in the field, with emphasis on magnetoelectric coupling effects in complex oxide multiferroic composite materials.
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Affiliation(s)
- Carlos A F Vaz
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA.
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27
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Kessler BM, Girit CO, Zettl A, Bouchiat V. Tunable superconducting phase transition in metal-decorated graphene sheets. PHYSICAL REVIEW LETTERS 2010; 104:047001. [PMID: 20366731 DOI: 10.1103/physrevlett.104.047001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Indexed: 05/29/2023]
Abstract
We have produced graphene sheets decorated with a nonpercolating network of nanoscale tin clusters. These metal clusters both efficiently dope the graphene substrate and induce long-range superconducting correlations. We find that despite structural inhomogeneity on mesoscopic length scales (10-100 nm), this material behaves electronically as a homogenous dirty superconductor with a field-effect tuned Berezinskii-Kosterlitz-Thouless transition. Our facile self-assembly method establishes graphene as an ideal tunable substrate for studying induced two-dimensional electronic systems at fixed disorder and our technique can readily be extended to other order parameters such as magnetism.
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Affiliation(s)
- B M Kessler
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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28
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Chambers SA. Epitaxial growth and properties of doped transition metal and complex oxide films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:219-248. [PMID: 20217685 DOI: 10.1002/adma.200901867] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The detailed science and technology of crystalline oxide film growth using vacuum methods is reviewed and discussed with an eye toward gaining fundamental insights into the relationships between growth process and parameters, film and interface structure and composition, and electronic, magnetic and photochemical properties. The topic is approached first from a comparative point of view based on the most widely used growth methods, and then on the basis of specific material systems that have generated very high levels of interest. Emphasis is placed on the wide diversity of structural, electronic, optical and magnetic properties exhibited by oxides, and the fascinating results that this diversity of properties can produce when combined with the degrees of freedom afforded by heteroepitaxy.
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Affiliation(s)
- Scott A Chambers
- Chemical and Materials Science Division, Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, PO Box 999, MS K8-87, Richland, WA 99352, USA.
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29
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Bell C, Harashima S, Kozuka Y, Kim M, Kim BG, Hikita Y, Hwang HY. Dominant mobility modulation by the electric field effect at the LaAlO3/SrTiO3 interface. PHYSICAL REVIEW LETTERS 2009; 103:226802. [PMID: 20366118 DOI: 10.1103/physrevlett.103.226802] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Indexed: 05/29/2023]
Abstract
Caviglia et al. [Nature (London) 456, 624 (2008)] have found that the superconducting LaAlO3/SrTiO3 interface can be gate modulated. A central issue is to determine the principal effect of the applied electric field. Using magnetotransport studies of a gated structure, we find that the mobility variation is almost 5 times that of the sheet carrier density. Furthermore, superconductivity can be suppressed at both positive and negative gate bias. These results indicate that the relative disorder strength strongly increases across the superconductor-insulator transition.
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Affiliation(s)
- C Bell
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8651, Japan
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30
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31
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Electric field control of the LaAlO3/SrTiO3 interface ground state. Nature 2008; 456:624-7. [PMID: 19052624 DOI: 10.1038/nature07576] [Citation(s) in RCA: 336] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Accepted: 10/20/2008] [Indexed: 11/08/2022]
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32
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Salluzzo M, Ghiringhelli G, Cezar JC, Brookes NB, De Luca GM, Fracassi F, Vaglio R. Indirect electric field doping of the CuO2 planes of the cuprate NdBa2Cu3O7 superconductor. PHYSICAL REVIEW LETTERS 2008; 100:056810. [PMID: 18352415 DOI: 10.1103/physrevlett.100.056810] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Indexed: 05/26/2023]
Abstract
The mechanism of field-effect doping in the 123 high critical temperature superconductors (HTS) has been investigated by x-ray absorption spectroscopy in the presence of an electric field. We demonstrate that holes are created at the CuO chains of the charge reservoir and that field-effect doping of the CuO(2) planes occurs by charge transfer, from the chains to the planes, of a fraction of the overall induced holes. The electronic properties of the charge reservoir and of the dielectric-HTS interface determine the electric field doping of the CuO(2) planes.
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Affiliation(s)
- M Salluzzo
- CNR-INFM COHERENTIA, Dipartimento di Scienze Fisiche Università di Napoli Federico II, Complesso di Monte S. Angelo, Via Cinthia, 80126 Napoli, Italy.
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33
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Takahashi KS, Gabay M, Jaccard D, Shibuya K, Ohnishi T, Lippmaa M, Triscone JM. Local switching of two-dimensional superconductivity using the ferroelectric field effect. Nature 2006; 441:195-8. [PMID: 16688171 DOI: 10.1038/nature04731] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Accepted: 03/16/2006] [Indexed: 11/09/2022]
Abstract
Correlated oxides display a variety of extraordinary physical properties including high-temperature superconductivity and colossal magnetoresistance. In these materials, strong electronic correlations often lead to competing ground states that are sensitive to many parameters--in particular the doping level--so that complex phase diagrams are observed. A flexible way to explore the role of doping is to tune the electron or hole concentration with electric fields, as is done in standard semiconductor field effect transistors. Here we demonstrate a model oxide system based on high-quality heterostructures in which the ferroelectric field effect approach can be studied. We use a single-crystal film of the perovskite superconductor Nb-doped SrTiO3 as the superconducting channel and ferroelectric Pb(Zr,Ti)O3 as the gate oxide. Atomic force microscopy is used to locally reverse the ferroelectric polarization, thus inducing large resistivity and carrier modulations, resulting in a clear shift in the superconducting critical temperature. Field-induced switching from the normal state to the (zero resistance) superconducting state was achieved at a well-defined temperature. This unique system could lead to a field of research in which devices are realized by locally defining in the same material superconducting and normal regions with 'perfect' interfaces, the interface being purely electronic. Using this approach, one could potentially design one-dimensional superconducting wires, superconducting rings and junctions, superconducting quantum interference devices (SQUIDs) or arrays of pinning centres.
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Affiliation(s)
- K S Takahashi
- DPMC, University of Geneva, 24 Quai Ernest Ansermet, 1211 Geneva 4, Switzerland
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