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Recent Developments in the Field of the Metal-Insulator Transition in Two Dimensions. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9061169] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We review the latest developments in the field of the metal-insulator transition in strongly-correlated two-dimensional electron systems. Particular attention is given to recent discoveries of a sliding quantum electron solid and interaction-induced spectrum flattening at the Fermi level in high-quality silicon-based structures.
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2
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Ash B, Chakrabarti J, Ghosal A. Static and dynamic properties of two-dimensional Coulomb clusters. Phys Rev E 2018; 96:042105. [PMID: 29347627 DOI: 10.1103/physreve.96.042105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Indexed: 11/07/2022]
Abstract
We study the temperature dependence of static and dynamic responses of Coulomb interacting particles in two-dimensional confinements across the crossover from solid- to liquid-like behaviors. While static correlations that investigate the translational and bond orientational order in the confinements show the footprints of hexatic-like phase at low temperatures, dynamics of the particles slow down considerably in this phase, reminiscent of a supercooled liquid. Using density correlations, we probe long-lived heterogeneities arising from the interplay of the irregularity in the confinement and long-range Coulomb interactions. The relaxation at multiple time scales show stretched-exponential decay of spatial correlations in irregular traps. Temperature dependence of characteristic time scales, depicting the structural relaxation of the system, show striking similarities with those observed for the glassy systems, indicating that some of the key signatures of supercooled liquids emerge in confinements with lower spatial symmetries.
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Affiliation(s)
- Biswarup Ash
- Indian Institute of Science Education and Research, Kolkata, Mohanpur 741246, India
| | - J Chakrabarti
- S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098, India
| | - Amit Ghosal
- Indian Institute of Science Education and Research, Kolkata, Mohanpur 741246, India
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Masutomi R, Sasaki K, Yasuda I, Sekine A, Sawano K, Shiraki Y, Okamoto T. Metallic behavior of cyclotron relaxation time in two-dimensional systems. PHYSICAL REVIEW LETTERS 2011; 106:196404. [PMID: 21668180 DOI: 10.1103/physrevlett.106.196404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Indexed: 05/30/2023]
Abstract
Cyclotron resonance of two-dimensional electrons is studied at low temperatures down to 0.4 K for a high-mobility Si/SiGe quantum well which exhibits a metallic temperature dependence of dc resistivity ρ. The relaxation time τ(CR) shows a negative temperature dependence, which is similar to that of the transport scattering time τ(t) obtained from ρ. The ratio τ(CR)/τ(t) at 0.4 K increases as the electron density N(s) decreases, and exceeds unity when N(s) approaches the critical density for the metal-insulator transition.
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Affiliation(s)
- Ryuichi Masutomi
- Department of Physics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Chakravarty S, Kivelson S, Nayak C, Voelker K. Wigner glass, spin liquids and the metal-insulator transition. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/13642819908214845] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Sudip Chakravarty
- a Department of Physics and Astronomy , University of California Los Angeles , Los Angeles , California , 90095-1547 , USA
| | - Steven Kivelson
- a Department of Physics and Astronomy , University of California Los Angeles , Los Angeles , California , 90095-1547 , USA
| | - Cheta Nayak
- a Department of Physics and Astronomy , University of California Los Angeles , Los Angeles , California , 90095-1547 , USA
| | - Klaus Voelker
- a Department of Physics and Astronomy , University of California Los Angeles , Los Angeles , California , 90095-1547 , USA
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Baenninger M, Ghosh A, Pepper M, Beere HE, Farrer I, Ritchie DA. Low-temperature collapse of electron localization in two dimensions. PHYSICAL REVIEW LETTERS 2008; 100:016805. [PMID: 18232805 DOI: 10.1103/physrevlett.100.016805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Indexed: 05/25/2023]
Abstract
We report direct experimental evidence that the insulating phase of a disordered, yet strongly interacting two-dimensional electron system becomes unstable at low temperatures. As the temperature decreases, a transition from insulating to metal-like transport behavior is observed, which persists even when the resistivity of the system greatly exceeds the quantum of resistivity h/e2. The results have been achieved by measuring transport on a mesoscopic length scale while systematically varying the strength of disorder.
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Affiliation(s)
- Matthias Baenninger
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
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Leturcq R, L'Hôte D, Tourbot R, Mellor CJ, Henini M. Resistance noise scaling in a dilute two-dimensional hole system in GaAs. PHYSICAL REVIEW LETTERS 2003; 90:076402. [PMID: 12633254 DOI: 10.1103/physrevlett.90.076402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2002] [Indexed: 05/24/2023]
Abstract
We have measured the resistance noise of a two-dimensional (2D) hole system in a high mobility GaAs quantum well, around the 2D metal-insulator transition (MIT) at zero magnetic field. The normalized noise power S(R)/R(2) increases strongly when the hole density p(s) is decreased, increases slightly with temperature (T) at the largest densities, and decreases strongly with T at low p(s). The noise scales with the resistance, S(R)/R(2) approximately R2.4, as for a second order phase transition such as a percolation transition. The p(s) dependence of the conductivity is consistent with a critical behavior for such a transition, near a density p(*) which is lower than the observed MIT critical density p(c).
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Affiliation(s)
- R Leturcq
- Service de Physique de l'Etat Condensé, CEA/DSM, CE Saclay, F-91191 Gif-sur-Yvette, France
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Shi J, Xie XC. Droplet state and the compressibility anomaly in dilute 2D electron systems. PHYSICAL REVIEW LETTERS 2002; 88:086401. [PMID: 11863965 DOI: 10.1103/physrevlett.88.086401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2001] [Indexed: 05/23/2023]
Abstract
We investigate the space distribution of carrier density and the compressibility of two-dimensional (2D) electron systems by using the local density approximation. The strong correlation is simulated by the local exchange and correlation energies. A slowly varied disorder potential is applied to simulate the disorder effect. We show that the compressibility anomaly observed in 2D systems which accompanies the metal-insulator transition can be attributed to the formation of the droplet state due to a disorder effect at low carrier densities.
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Affiliation(s)
- Junren Shi
- Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, USA
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Ilani S, Yacoby A, Mahalu D, Shtrikman H. Microscopic Structure of the Metal-Insulator Transition in Two Dimensions. Science 2001; 292:1354-7. [PMID: 11359006 DOI: 10.1126/science.1058645] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A single electron transistor is used as a local electrostatic probe to study the underlying spatial structure of the metal-insulator transition in two dimensions. The measurements show that as we approach the transition from the metallic side, a new phase emerges that consists of weakly coupled fragments of the two-dimensional system. These fragments consist of localized charge that coexists with the surrounding metallic phase. As the density is lowered into the insulating phase, the number of fragments increases on account of the disappearing metallic phase. The measurements reveal that the metal-insulator transition is a result of the microscopic restructuring that occurs in the system.
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Affiliation(s)
- S Ilani
- Braun Center for Submicron Research, Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
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Reichhardt C, Olson CJ, Grønbech-Jensen N, Nori F. Moving Wigner glasses and smectics: dynamics of disordered Wigner crystals. PHYSICAL REVIEW LETTERS 2001; 86:4354-4357. [PMID: 11328173 DOI: 10.1103/physrevlett.86.4354] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2000] [Indexed: 05/23/2023]
Abstract
We examine the dynamics of driven classical Wigner solids interacting with quenched disorder from charged impurities. For strong disorder, the initial motion is plastic, in the form of crossing winding channels. For increasing drive, there is a reordering into a moving Wigner smectic with the electrons moving in separate 1D channels. These different dynamic phases can be related to the conduction noise and I(V) curves. For strong disorder, we show criticality in the voltage onset just above depinning. We obtain the dynamic phase diagram for driven Wigner solids and demonstrate a finite threshold of force for transverse sliding, recently observed experimentally.
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Affiliation(s)
- C Reichhardt
- Department of Physics, University of California, Davis, California 95616, USA
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Bernu B, Cândido L, Ceperley DM. Exchange frequencies in the 2D Wigner crystal. PHYSICAL REVIEW LETTERS 2001; 86:870-873. [PMID: 11177961 DOI: 10.1103/physrevlett.86.870] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2000] [Indexed: 05/23/2023]
Abstract
Using path integral Monte Carlo we have calculated exchange frequencies as electrons undergo ring exchanges in a "clean" 2D Wigner crystal as a function of density. The results show agreement with WKB calculations at very low density, but show a more rapid increase with density near melting. Remarkably, the exchange Hamiltonian closely resembles the measured exchanges in 2D (3)He. Using the resulting multispin exchange model we find the spin Hamiltonian for r(s) < or = 175 +/- 10 is a frustrated antiferromagnetic; its likely ground state is a spin liquid. For lower density the ground state will be ferromagnetic.
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Affiliation(s)
- B Bernu
- Laboratoire de Physique Théorique des Liquides, UMR 7600 of CNRS, Université Pierre et Marie Curie, Paris, France
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Cândido L, Phillips P, Ceperley DM. Single and paired point defects in a 2D Wigner crystal. PHYSICAL REVIEW LETTERS 2001; 86:492-495. [PMID: 11177863 DOI: 10.1103/physrevlett.86.492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2000] [Indexed: 05/23/2023]
Abstract
Using the path-integral Monte Carlo method, we calculate the energy to form single and pair vacancies and interstitials in a two-dimensional Wigner crystal of electrons. We confirm that the lowest energy point defects of a 2D electron Wigner crystal are interstitials, with a creation energy roughly 2/3 that of a vacancy. The formation energy of the defects goes to zero at melting, suggesting that point defects may be the melting mechanism and that the melting could be a continuous transition. In addition, we find that the interaction between defects is strongly attractive, so that most defects will exist as bound pairs.
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Affiliation(s)
- L Cândido
- Loomis Laboratory of Physics and NCSA, University of Illinois at Urbana-Champaign, 1100 West Green Street, Urbana, Illinois 61801-3080, USA
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Zhitenev NB, Brodsky M, Ashoori RC, Pfeiffer LN, West KW. Localization-delocalization transition in quantum dots. Science 1999; 285:715-8. [PMID: 10426989 DOI: 10.1126/science.285.5428.715] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Single-electron capacitance spectroscopy precisely measures the energies required to add individual electrons to a quantum dot. The spatial extent of electronic wave functions is probed by investigating the dependence of these energies on changes in the dot confining potential. For low electron densities, electrons occupy distinct spatial sites localized within the dot. At higher densities, the electrons become delocalized, and all wave functions are spread over the full dot area. Near the delocalization transition, the last remaining localized states exist at the perimeter of the dot. Unexpectedly, these electrons appear to bind with electrons in the dot center.
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Affiliation(s)
- NB Zhitenev
- Department of Physics and Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, USA
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Phillips P, Wan Y, Martin I, Knysh S, Dalidovich D. Superconductivity in a two-dimensional electron gas. Nature 1998. [DOI: 10.1038/26179] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Thakur JS, Neilson D. Frozen electron solid in the presence of small concentrations of defects. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:7674-7677. [PMID: 9984433 DOI: 10.1103/physrevb.54.7674] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Zheng L, Fertig HA. The Hofstadter spectrum of the Wigner crystal. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:R2321-R2324. [PMID: 9981401 DOI: 10.1103/physrevb.52.r2321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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