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Valenti A, Calvera V, Kivelson SA, Berg E, Huber SD. Nematic Metal in a Multivalley Electron Gas: Variational Monte Carlo Analysis and Application to AlAs. PHYSICAL REVIEW LETTERS 2024; 132:266501. [PMID: 38996276 DOI: 10.1103/physrevlett.132.266501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 01/17/2024] [Accepted: 04/26/2024] [Indexed: 07/14/2024]
Abstract
The two-dimensional electron gas is of fundamental importance in quantum many-body physics. We study a minimal extension of this model with C_{4} (as opposed to full rotational) symmetry and an electronic dispersion with two valleys with anisotropic effective masses. Electrons in our model interact via Coulomb repulsion, screened by distant metallic gates. Using variational Monte Carlo simulations, we find a broad intermediate range of densities with a metallic valley-polarized, spin-unpolarized ground state. Our results are of direct relevance to the recently discovered "nematic" state in AlAs quantum wells. For the effective mass anisotropy relevant to this system, m_{x}/m_{y}≈5.2, we obtain a transition from an anisotropic metal to a valley-polarized metal at r_{s}≈12 (where r_{s} is the dimensionless Wigner-Seitz radius). At still lower densities, we find a (possibly metastable) valley and spin-polarized state with a reduced electronic anisotropy.
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T. T. Le P, Davoudiniya M, Yarmohammadi M. Interplay of orbital hopping and perpendicular magnetic field in anisotropic phase transitions for Bernal bilayer graphene and hexagonal boron-nitride. Phys Chem Chem Phys 2019; 21:238-245. [DOI: 10.1039/c8cp05810e] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We theoretically address the perpendicular magnetic field effects on the orbital electronic phase of Bernal bilayer graphene and hexagonal boron-nitride (h-BN).
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Affiliation(s)
- P. T. T. Le
- Theoretical Physics Research Group, Advanced Institute of Materials Science
- Ton Duc Thang University
- Ho Chi Minh City
- Vietnam
- Faculty of Applied Sciences
| | - M. Davoudiniya
- Department of Energy Engineering and Physics
- Amirkabir University of Technology
- 14588 Tehran
- Iran
| | - M. Yarmohammadi
- Lehrstuhl für Theoretische Physik I
- Technische Universität Dortmund
- 44221 Dortmund
- Germany
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Perez F, Baboux F, Ullrich CA, D'Amico I, Vignale G, Karczewski G, Wojtowicz T. Spin-Orbit Twisted Spin Waves: Group Velocity Control. PHYSICAL REVIEW LETTERS 2016; 117:137204. [PMID: 27715118 DOI: 10.1103/physrevlett.117.137204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 06/06/2023]
Abstract
We present a theoretical and experimental study of the interplay between spin-orbit coupling (SOC), Coulomb interaction, and motion of conduction electrons in a magnetized two-dimensional electron gas. Via a transformation of the many-body Hamiltonian we introduce the concept of spin-orbit twisted spin waves, whose energy dispersions and damping rates are obtained by a simple wave-vector shift of the spin waves without SOC. These theoretical predictions are validated by Raman scattering measurements. With optical gating of the density, we vary the strength of the SOC to alter the group velocity of the spin wave. The findings presented here differ from that of spin systems subject to the Dzyaloshinskii-Moriya interaction. Our results pave the way for novel applications in spin-wave routing devices and for the realization of lenses for spin waves.
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Affiliation(s)
- F Perez
- Institut des Nanosciences de Paris, CNRS/Université Paris VI, Paris 75005, France
| | - F Baboux
- Institut des Nanosciences de Paris, CNRS/Université Paris VI, Paris 75005, France
- Laboratoire de Photonique et de Nanostructures, LPN/CNRS, 91460 Marcoussis, France
| | - C A Ullrich
- Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA
| | - I D'Amico
- Department of Physics, University of York, York YO10 5DD, United Kingdom
| | - G Vignale
- Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA
| | - G Karczewski
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - T Wojtowicz
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
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Renard VT, Piot BA, Waintal X, Fleury G, Cooper D, Niida Y, Tregurtha D, Fujiwara A, Hirayama Y, Takashina K. Valley polarization assisted spin polarization in two dimensions. Nat Commun 2015; 6:7230. [PMID: 26027889 PMCID: PMC4458877 DOI: 10.1038/ncomms8230] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 04/20/2015] [Indexed: 11/15/2022] Open
Abstract
Valleytronics is rapidly emerging as an exciting area of basic and applied research. In two-dimensional systems, valley polarization can dramatically modify physical properties through electron-electron interactions as demonstrated by such phenomena as the fractional quantum Hall effect and the metal-insulator transition. Here, we address the electrons' spin alignment in a magnetic field in silicon-on-insulator quantum wells under valley polarization. In stark contrast to expectations from a non-interacting model, we show experimentally that less magnetic field can be required to fully spin polarize a valley-polarized system than a valley-degenerate one. Furthermore, we show that these observations are quantitatively described by parameter-free ab initio quantum Monte Carlo simulations. We interpret the results as a manifestation of the greater stability of the spin- and valley-degenerate system against ferromagnetic instability and Wigner crystalization, which in turn suggests the existence of a new strongly correlated electron liquid at low electron densities.
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Affiliation(s)
- V. T. Renard
- Université Grenoble Alpes/CEA, INAC-SPSMS, F-38000, Grenoble, France
| | - B. A. Piot
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA-EMFL, 38042, Grenoble, France
| | - X. Waintal
- Université Grenoble Alpes/CEA, INAC-SPSMS, F-38000, Grenoble, France
| | - G. Fleury
- Service de Physique de l'État Condensé, DSM/IRAMIS/SPEC, CNRS UMR 3680 CEA Saclay, 91191 Gif sur Yvette, France
| | - D. Cooper
- Université Grenoble Alpes/CEA Leti Minatec campus, F-38054, Grenoble, France
| | - Y. Niida
- Graduate School of Science, Tohoku University, 6-3 Aramakiaza Aoba, Aobaku, Sendai, 980-8578, Japan
| | - D. Tregurtha
- Department of Physics, University of Bath, Bath, BA2 7AY, UK
| | - A. Fujiwara
- NTT Basic Research Laboratories, NTT Corporation, Atsugi-shi, Kanagawa, 243-0198, Japan
| | - Y. Hirayama
- Graduate School of Science, Tohoku University, 6-3 Aramakiaza Aoba, Aobaku, Sendai, 980-8578, Japan
| | - K. Takashina
- Department of Physics, University of Bath, Bath, BA2 7AY, UK
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Perez F, Aku-leh C, Richards D, Jusserand B, Smith LC, Wolverson D, Karczewski G. From spin flip excitations to the spin susceptibility enhancement of a two-dimensional electron gas. PHYSICAL REVIEW LETTERS 2007; 99:026403. [PMID: 17678240 DOI: 10.1103/physrevlett.99.026403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2006] [Indexed: 05/16/2023]
Abstract
The g-factor enhancement of the spin-polarized two-dimensional electron gas was measured directly over a wide range of spin polarizations, using spin flip resonant Raman scattering spectroscopy on two-dimensional electron gases embedded in Cd(1-x)Mn(x)Te semimagnetic quantum wells. At zero Raman transferred momentum, the single-particle spin flip excitation, energy Z*, coexists in the Raman spectrum with the spin flip wave of energy Z, the bare giant Zeeman splitting. We compare the measured g-factor enhancement with recent spin-susceptibility enhancement theories and deduce the spin-polarization dependence of the mass renormalization.
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Affiliation(s)
- F Perez
- Institut des NanoSciences de Paris, CNRS, Universités Paris 6 and 7, 140 rue de Lourmel, 75015 Paris, France
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Zhang Y, Sarma SD. Comment on "effects of thickness on the spin susceptibility of the two dimensional electron gas". PHYSICAL REVIEW LETTERS 2006; 97:039701; author reply 039702. [PMID: 16907551 DOI: 10.1103/physrevlett.97.039701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Indexed: 05/11/2023]
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Casula M, Senatore G. Charge and spin correlations of a one-dimensional electron gas on the continuum. Chemphyschem 2005; 6:1902-5. [PMID: 16144015 DOI: 10.1002/cphc.200500093] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We present a variational Monte Carlo study of a model one-dimensional electron gas on the continuum, with long-range interaction (1/r decay). At low density, the reduced dimensionality brings about pseudonodes of the many-body wavefunction, yielding nonergodic behavior of naive Monte Carlo sampling, which affects the evaluation of pair correlations and the related structure factors. The problem is, however, easily solved, and we carefully analyzed the structure factors obtained from an optimal trial function, finding good agreement with the exact predictions for a Luttinger-like Hamiltonian with an interaction similar to the one used in the present study.
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Affiliation(s)
- Michele Casula
- International School for Advanced Studies (SISSA), Via Beirut 2,4 34014 Trieste, Italy
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