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Spin effect on the low-temperature resistivity maximum in a strongly interacting 2D electron system. Sci Rep 2022; 12:5080. [PMID: 35332223 PMCID: PMC8948273 DOI: 10.1038/s41598-022-09034-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/16/2022] [Indexed: 11/08/2022] Open
Abstract
The increase in the resistivity with decreasing temperature followed by a drop by more than one order of magnitude is observed on the metallic side near the zero-magnetic-field metal-insulator transition in a strongly interacting two-dimensional electron system in ultra-clean SiGe/Si/SiGe quantum wells. We find that the temperature [Formula: see text], at which the resistivity exhibits a maximum, is close to the renormalized Fermi temperature. However, rather than increasing along with the Fermi temperature, the value [Formula: see text] decreases appreciably for spinless electrons in spin-polarizing (parallel) magnetic fields. The observed behaviour of [Formula: see text] cannot be described by existing theories. The results indicate the spin-related origin of the effect.
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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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Lin PV, Popović D. Critical Behavior of a Strongly Disordered 2D Electron System: The Cases of Long-Range and Screened Coulomb Interactions. PHYSICAL REVIEW LETTERS 2015; 114:166401. [PMID: 25955059 DOI: 10.1103/physrevlett.114.166401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Indexed: 06/04/2023]
Abstract
A study of the temperature (T) and density (ns) dependence of conductivity σ(ns,T) of a highly disordered, two-dimensional (2D) electron system in Si demonstrates scaling behavior consistent with the existence of a metal-insulator transition (MIT). The same critical exponents are found when the Coulomb interaction is screened by the metallic gate and when it is unscreened or long range. The results strongly suggest the existence of a disorder-dominated 2D MIT, which is not directly affected by the range of the Coulomb interactions.
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Affiliation(s)
- Ping V Lin
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Dragana Popović
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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Tracy LA, Eisenstein JP, Pfeiffer LN, West KW. Spin transition in the half-filled Landau level. PHYSICAL REVIEW LETTERS 2007; 98:086801. [PMID: 17359116 DOI: 10.1103/physrevlett.98.086801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2006] [Indexed: 05/14/2023]
Abstract
The transition from partial to complete spin polarization of two-dimensional electrons at half filling of the lowest Landau level has been studied using resistively detected nuclear magnetic resonance (RDNMR). The nuclear spin-lattice relaxation time is observed to be density independent in the partially polarized phase but to increase sharply at the transition to full polarization. At low temperatures the RDNMR signal exhibits a strong maximum near the critical density.
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Affiliation(s)
- L A Tracy
- California Institute of Technology, Pasadena, CA 91125, USA
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Anissimova S, Venkatesan A, Shashkin AA, Sakr MR, Kravchenko SV, Klapwijk TM. Magnetization of a strongly interacting two-dimensional electron system in perpendicular magnetic fields. PHYSICAL REVIEW LETTERS 2006; 96:046409. [PMID: 16486862 DOI: 10.1103/physrevlett.96.046409] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2005] [Indexed: 05/06/2023]
Abstract
We measure the thermodynamic magnetization of a low-disordered, strongly correlated two-dimensional electron system in silicon in perpendicular magnetic fields. A new, parameter-free method is used to directly determine the spectrum characteristics (Landé g factor and the cyclotron mass) when the Fermi level lies outside the spectral gaps and the interlevel interactions between quasiparticles are avoided. Intralevel interactions are found to strongly modify the magnetization, without affecting the determined g* and m*.
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Affiliation(s)
- S Anissimova
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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Gangadharaiah S, Maslov DL. Spin-independent effective mass in a valley-degenerate electron system. PHYSICAL REVIEW LETTERS 2005; 95:186801. [PMID: 16383933 DOI: 10.1103/physrevlett.95.186801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Indexed: 05/05/2023]
Abstract
In a generic spin-polarized Fermi liquid, the masses of spin-up and spin-down electrons are expected to be different and to depend on the degree of polarization. This expectation is not confirmed by the experiments on two-dimensional heterostructures. We consider a model of an N-fold degenerate electron gas. It is shown that in the large- limit, the mass is enhanced via a polaronic mechanism of emission or absorption of virtual plasmons. As plasmons are classical collective excitations, the resulting mass does not depend on , and thus on polarization, to the leading order in 1/N. We evaluate the 1/N corrections and show that they are small even for N = 2.
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Affiliation(s)
- Suhas Gangadharaiah
- Department of Physics, University of Florida, P.O. Box 118440, Gainesville, Florida 32611-8440, USA
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Jaroszyński J, Popović D, Klapwijk TM. Magnetic-field dependence of the anomalous noise behavior in a two-dimensional electron system in silicon. PHYSICAL REVIEW LETTERS 2004; 92:226403. [PMID: 15245243 DOI: 10.1103/physrevlett.92.226403] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2003] [Indexed: 05/24/2023]
Abstract
Studies of low-frequency resistance noise show that the dramatic change in the dynamics of the two-dimensional electron system (2DES) in Si that occurs near the metal-insulator transition (MIT) persists in high parallel magnetic fields B such that the 2DES is fully spin polarized. This strongly suggests that charge, as opposed to spin, degrees of freedom are responsible for this effect. In the metallic phase, however, noise is suppressed by a parallel B, pointing to the role of spins. At low B, the temperature dependence of conductivity in the metallic phase provides evidence for a MIT.
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Affiliation(s)
- J Jaroszyński
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
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Zhu J, Stormer HL, Pfeiffer LN, Baldwin KW, West KW. Spin susceptibility of an ultra-low-density two-dimensional electron system. PHYSICAL REVIEW LETTERS 2003; 90:056805. [PMID: 12633387 DOI: 10.1103/physrevlett.90.056805] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2002] [Indexed: 05/24/2023]
Abstract
We determine the spin susceptibility in a two-dimensional electron system in GaAs/AlGaAs over a wide range of low densities from 2x10(9) cm(-2) to 4x10(10) cm(-2). Our data can be fitted to an equation that describes the density dependence as well as the polarization dependence of the spin susceptibility. It can account for the anomalous g factors reported recently in GaAs electron and hole systems. The paramagnetic spin susceptibility increases with decreasing density as expected from theoretical calculations.
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Affiliation(s)
- J Zhu
- Department of Physics, Columbia University, New York, New York 10027, USA
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Dolgopolov VT, Gold A. Comment on "weak anisotropy and disorder dependence of the in-plane magnetoresistance in high-mobility (100) si-inversion layers". PHYSICAL REVIEW LETTERS 2002; 89:129701. [PMID: 12225129 DOI: 10.1103/physrevlett.89.129701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2002] [Indexed: 05/23/2023]
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Eng K, Feng XG, Popović D, Washburn S. Effects of a parallel magnetic field on the metal-insulator transition in a dilute two-dimensional electron system. PHYSICAL REVIEW LETTERS 2002; 88:136402. [PMID: 11955112 DOI: 10.1103/physrevlett.88.136402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2001] [Indexed: 05/23/2023]
Abstract
The temperature dependence of conductivity sigma(T) of a two-dimensional electron system in silicon has been studied in parallel magnetic fields B. At B = 0, the system displays a metal-insulator transition at a critical electron density n(c)(0), and dsigma/dT>0 in the metallic phase. At low fields ( B < or approximately equal to 2 T), n(c) increases as n(c)(B)-n(c)(0) proportional, variant Bbeta ( beta approximately 1), and the zero-temperature conductivity scales as sigma(n(s),B,T = 0)/sigma(n(s),0,0) = f(B(beta)/delta(n)), where delta(n) = [n(s)-n(c)(0)]/n(c)(0) and n(s) is electron density, as expected for a quantum phase transition. The metallic phase persists in fields of up to 18 T, consistent with the saturation of n(c) at high fields.
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Affiliation(s)
- Kevin Eng
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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Shashkin AA, Kravchenko SV, Klapwijk TM. Metal-insulator transition in a 2D electron gas: equivalence of two approaches for determining the critical point. PHYSICAL REVIEW LETTERS 2001; 87:266402. [PMID: 11800848 DOI: 10.1103/physrevlett.87.266402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2001] [Indexed: 05/23/2023]
Abstract
The critical electron density for the metal-insulator transition in a two-dimensional electron gas can be determined by two distinct methods: (i) a sign change of the temperature derivative of the resistance, and (ii) vanishing activation energy and vanishing nonlinearity of current-voltage characteristics as extrapolated from the insulating side. We find that, in zero magnetic field (but not in the presence of a parallel magnetic field), both methods give equivalent results, adding support to the existence of a true zero-field metal-insulator transition.
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Affiliation(s)
- A A Shashkin
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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Shashkin AA, Kravchenko SV, Dolgopolov VT, Klapwijk TM. Indication of the ferromagnetic instability in a dilute two-dimensional electron system. PHYSICAL REVIEW LETTERS 2001; 87:086801. [PMID: 11497969 DOI: 10.1103/physrevlett.87.086801] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2001] [Indexed: 05/23/2023]
Abstract
The magnetic field B(c), in which the electrons become fully spin polarized, is found to be proportional to the deviation of the electron density from the zero-field metal-insulator transition in a two-dimensional electron system in silicon. The tendency of B(c) to vanish at a finite electron density suggests a ferromagnetic instability in this strongly correlated electron system.
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Affiliation(s)
- A A Shashkin
- Physics Department, Northeastern University, Boston, Massachusetts 02115, USA
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Vitkalov SA, Zheng H, Mertes KM, Sarachik MP, Klapwijk TM. Scaling of the magnetoconductivity of silicon MOSFETs: evidence for a quantum phase transition in two dimensions. PHYSICAL REVIEW LETTERS 2001; 87:086401. [PMID: 11497966 DOI: 10.1103/physrevlett.87.086401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2000] [Revised: 05/08/2001] [Indexed: 05/23/2023]
Abstract
For a broad range of electron densities n and temperatures T, the in-plane magnetoconductivity of the two-dimensional system of electrons in silicon MOSFETs can be scaled onto a universal curve with a single parameter H(sigma)(n,T), where H(sigma) obeys the empirical relation H(sigma) = A(n) [Delta(n)(2)+T2](1/2). The characteristic energy k(B)Delta associated with the magnetic field dependence of the conductivity decreases with decreasing density, and extrapolates to 0 at a critical density n(0), signaling the approach to a zero-temperature quantum phase transition. We show that H(sigma) = AT for densities near n(0).
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Affiliation(s)
- S A Vitkalov
- Physics Department, City College of the City University of New York, New York, New York 10031, USA
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Tutuc E, De Poortere EP, Papadakis SJ, Shayegan M. In-plane magnetic field-induced spin polarization and transition to insulating behavior in two-dimensional hole systems. PHYSICAL REVIEW LETTERS 2001; 86:2858-2861. [PMID: 11290057 DOI: 10.1103/physrevlett.86.2858] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2000] [Indexed: 05/23/2023]
Abstract
Using a novel technique, we make quantitative measurements of the spin polarization of dilute [ (3.4-6.8)x10(10) cm(-2)] GaAs (311)A two-dimensional holes as a function of an in-plane magnetic field. As the field is increased the system gradually becomes spin polarized, with the degree of spin polarization depending on the orientation of the field relative to the crystal axes. Moreover, the behavior of the system turns from metallic to insulating before it is fully spin polarized. The minority-spin population at the transition is approximately 8x10(9) cm(-2), close to the density below which the system makes a transition to an insulating state in the absence of a magnetic field.
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Affiliation(s)
- E Tutuc
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
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