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Kumar AS, Liu CW, Liu S, Gao XPA, Levchenko A, Pfeiffer LN, West KW. Anomalous High-Temperature Magnetoresistance in a Dilute 2D Hole System. PHYSICAL REVIEW LETTERS 2023; 130:266302. [PMID: 37450788 DOI: 10.1103/physrevlett.130.266302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 08/15/2022] [Accepted: 06/02/2023] [Indexed: 07/18/2023]
Abstract
We report an unusual magnetoresistance that strengthens with the temperature in a dilute two-dimensional (2D) hole system in GaAs/AlGaAs quantum wells with densities p=1.98-0.99×10^{10}/cm^{2} where r_{s}, the ratio between Coulomb energy and Fermi energy, is as large as 20-30. We show that, while the system exhibits a negative parabolic magnetoresistance at low temperatures (≲0.4 K) characteristic of an interacting Fermi liquid, a positive magnetoresistance emerges unexpectedly at higher temperatures, and grows with increasing temperature even in the regime T∼E_{F}, close to the Fermi energy. This unusual positive magnetoresistance at high temperatures can be attributed to the viscous transport of 2D hole fluid in the hydrodynamic regime where holes scatter frequently with each other. These findings give insight into the collective transport of strongly interacting carriers in the r_{s}≫1 regime and new routes toward magnetoresistance at high temperatures.
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Affiliation(s)
- Arvind Shankar Kumar
- Department of Physics, Case Western Reserve University, 2076 Adelbert Road, Cleveland, Ohio 44106, USA
| | - Chieh-Wen Liu
- Department of Physics, Case Western Reserve University, 2076 Adelbert Road, Cleveland, Ohio 44106, USA
| | - Shuhao Liu
- Department of Physics, Case Western Reserve University, 2076 Adelbert Road, Cleveland, Ohio 44106, USA
| | - Xuan P A Gao
- Department of Physics, Case Western Reserve University, 2076 Adelbert Road, Cleveland, Ohio 44106, USA
| | - Alex Levchenko
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Loren N Pfeiffer
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Kenneth W West
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
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Ma MK, Villegas Rosales KA, Deng H, Chung YJ, Pfeiffer LN, West KW, Baldwin KW, Winkler R, Shayegan M. Thermal and Quantum Melting Phase Diagrams for a Magnetic-Field-Induced Wigner Solid. PHYSICAL REVIEW LETTERS 2020; 125:036601. [PMID: 32745416 DOI: 10.1103/physrevlett.125.036601] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 06/12/2020] [Indexed: 06/11/2023]
Abstract
A sufficiently large perpendicular magnetic field quenches the kinetic (Fermi) energy of an interacting two-dimensional (2D) system of fermions, making them susceptible to the formation of a Wigner solid (WS) phase in which the charged carriers organize themselves in a periodic array in order to minimize their Coulomb repulsion energy. In low-disorder 2D electron systems confined to modulation-doped GaAs heterostructures, signatures of a magnetic-field-induced WS appear at low temperatures and very small Landau level filling factors (ν≃1/5). In dilute GaAs 2D hole systems, on the other hand, thanks to the larger hole effective mass and the ensuing Landau level mixing, the WS forms at relatively higher fillings (ν≃1/3). Here we report our measurements of the fundamental temperature vs filling phase diagram for the 2D holes' WS-liquid thermal melting. Moreover, via changing the 2D hole density, we also probe their Landau level mixing vs filling WS-liquid quantum melting phase diagram. We find our data to be in good agreement with the results of very recent calculations, although intriguing subtleties remain.
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Affiliation(s)
- Meng K Ma
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - K A Villegas Rosales
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - H Deng
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Y J Chung
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - L N Pfeiffer
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - K W West
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - K W Baldwin
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - R Winkler
- Department of Physics, Northern Illinois University, DeKalb, Illinois 60115, USA
| | - M Shayegan
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
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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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Abstract
Transport results from measuring ultra-clean two-dimensional systems, containing tunable carrier densities from 7 × 10 8 cm − 2 to ∼ 1 × 10 10 cm − 2 , reveal a strongly correlated liquid up to r s ≈ 40 where a Wigner crystallization is anticipated. A critical behavior is identified in the proximity of the metal-to-insulator transition. The nonlinear DC responses for r s > 40 captures hard pinning modes that likely undergo a first order transition into an intermediate phase in the course of melting.
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New Reentrant Insulating Phases in Strongly Interacting 2D Systems with Low Disorder. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8101909] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The metal-insulator transition (MIT) in two-dimension (2D) was discovered by Kravchenko et al. more than two decades ago in strongly interacting 2D electrons residing in a Si-metal-oxide-semiconductor field-effect transistor (Si-MOSFET). Its origin remains unresolved. Recently, low magnetic field reentrant insulating phases (RIPs), which dwell between the zero-field (B = 0) metallic state and the integer quantum Hall (QH) states where the Landau-level filling factor υ > 1, have been observed in strongly correlated 2D GaAs hole systems with a large interaction parameter, rs, (~20–40) and a high purity. A new complex phase diagram was proposed, which includes zero-field MIT, low magnetic field RIPs, integer QH states, fractional QH states, high field RIPs and insulating phases (HFIPs) with υ < 1 in which the insulating phases are explained by the formation of a Wigner crystal. Furthermore, evidence of new intermediate phases was reported. This review article serves the purpose of summarizing those recent experimental findings and theoretical endeavors to foster future research efforts.
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Transport evidence for a sliding two-dimensional quantum electron solid. Nat Commun 2018; 9:3803. [PMID: 30228256 PMCID: PMC6143544 DOI: 10.1038/s41467-018-06332-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 08/22/2018] [Indexed: 11/08/2022] Open
Abstract
Ignited by the discovery of the metal-insulator transition, the behaviour of low-disorder two-dimensional (2D) electron systems is currently the focus of a great deal of attention. In the strongly interacting limit, electrons are expected to crystallize into a quantum Wigner crystal, but no definitive evidence for this effect has been obtained despite much experimental effort over the years. Here, studying the insulating state of a 2D electron system in silicon, we have found two-threshold voltage-current characteristics with a dramatic increase in noise between the two threshold voltages. This behaviour cannot be described within existing traditional models. On the other hand, it is strikingly similar to that observed for the collective depinning of the vortex lattice in type-II superconductors. Adapting the model used for vortexes to the case of an electron solid yields good agreement with our experimental results, favouring the quantum electron solid as the origin of the low-density state.
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Osofsky MS, Krowne CM, Charipar KM, Bussmann K, Chervin CN, Pala IR, Rolison DR. Disordered RuO2 exhibits two dimensional, low-mobility transport and a metal-insulator transition. Sci Rep 2016; 6:21836. [PMID: 26915411 PMCID: PMC4768250 DOI: 10.1038/srep21836] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 09/18/2015] [Indexed: 11/28/2022] Open
Abstract
The discovery of low-dimensional metallic systems such as high-mobility metal oxide field-effect transistors, the cuprate superconductors, and conducting oxide interfaces (e.g., LaAlO3/SrTiO3) has stimulated research into the nature of electronic transport in two-dimensional systems given that the seminal theory for transport in disordered metals predicts that the metallic state cannot exist in two dimensions (2D). In this report, we demonstrate the existence of a metal–insulator transition (MIT) in highly disordered RuO2 nanoskins with carrier concentrations that are one-to-six orders of magnitude higher and with mobilities that are one-to-six orders of magnitude lower than those reported previously for 2D oxides. The presence of an MIT and the accompanying atypical electronic characteristics place this form of the oxide in a highly diffusive, strong disorder regime and establishes the existence of a metallic state in 2D that is analogous to the three-dimensional case.
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Affiliation(s)
- M S Osofsky
- Materials and Sensors Branch (Code 6360), U.S. Naval Research Laboratory, Washington, DC 20375, USA
| | - C M Krowne
- Electromagnetics Technology Branch (Code 6850), U.S. Naval Research Laboratory, Washington, DC 20375, USA
| | - K M Charipar
- Materials and Sensors Branch (Code 6360), U.S. Naval Research Laboratory, Washington, DC 20375, USA
| | - K Bussmann
- Materials and Sensors Branch (Code 6360), U.S. Naval Research Laboratory, Washington, DC 20375, USA
| | - C N Chervin
- Surface Chemistry Branch (Code 6170), U.S. Naval Research Laboratory, Washington, DC 20375, USA
| | - I R Pala
- Surface Chemistry Branch (Code 6170), U.S. Naval Research Laboratory, Washington, DC 20375, USA
| | - D R Rolison
- Surface Chemistry Branch (Code 6170), U.S. Naval Research Laboratory, Washington, DC 20375, USA
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Kuntsevich AY, Pudalov VM. Comment on "Connecting the reentrant insulating phase and the zero-field metal-insulator transition in a 2D hole system". PHYSICAL REVIEW LETTERS 2013; 110:249701. [PMID: 25165970 DOI: 10.1103/physrevlett.110.249701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Indexed: 06/03/2023]
Abstract
A Comment on the Letter by R. L. J. Qiu et al., Phys. Rev. Lett. 108, 106404 (2012). The authors of the Letter offer a Reply.
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Affiliation(s)
- A Yu Kuntsevich
- P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991, Russia
| | - V M Pudalov
- P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991, Russia and Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia
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9
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Abstract
A reply to the comment by A. Yu. Kuntsevich and V. M. Pudalov.
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Affiliation(s)
- R L J Qiu
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - X P A Gao
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106, USA
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