Theory of Coulomb driven nematicity in a multi-valley two-dimensional electron gas
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| Main Authors: | , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866915374164869120 |
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| author | Calvera, Vladimir Valenti, Agnes Huber, Sebastian D. Berg, Erez Kivelson, Steven A. |
| author_facet | Calvera, Vladimir Valenti, Agnes Huber, Sebastian D. Berg, Erez Kivelson, Steven A. |
| contents | The properties of a two-dimensional electron gas (2DEG) in a semiconductor host with two valleys related by an underlying $C_4$ rotational symmetry are studied using Hartree-Fock (HF) and various other many-body approaches. A familiar artifact of the HF approach is a degeneracy between the valley polarized - ``Ising nematic'' - and spin polarized - ferromagnetic - phases, which is inconsistent with recent variational Monte Carlo (VMC) results. Correlation effects, computed either within the random phase approximation (RPA) or the T-matrix approximation, enhance the valley susceptibility relative to the spin susceptibility. Extrapolating the results to finite interaction strength, we find a direct first-order transition from a symmetry-unbroken state to a spin unpolarized Ising nematic fluid with full valley polarization, in qualitative agreement with VMC. The RPA results are also reminiscent of experiments on the corresponding 2DEG in AlAs heterostructures. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2406_12825 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Theory of Coulomb driven nematicity in a multi-valley two-dimensional electron gas Calvera, Vladimir Valenti, Agnes Huber, Sebastian D. Berg, Erez Kivelson, Steven A. Strongly Correlated Electrons Mesoscale and Nanoscale Physics Statistical Mechanics The properties of a two-dimensional electron gas (2DEG) in a semiconductor host with two valleys related by an underlying $C_4$ rotational symmetry are studied using Hartree-Fock (HF) and various other many-body approaches. A familiar artifact of the HF approach is a degeneracy between the valley polarized - ``Ising nematic'' - and spin polarized - ferromagnetic - phases, which is inconsistent with recent variational Monte Carlo (VMC) results. Correlation effects, computed either within the random phase approximation (RPA) or the T-matrix approximation, enhance the valley susceptibility relative to the spin susceptibility. Extrapolating the results to finite interaction strength, we find a direct first-order transition from a symmetry-unbroken state to a spin unpolarized Ising nematic fluid with full valley polarization, in qualitative agreement with VMC. The RPA results are also reminiscent of experiments on the corresponding 2DEG in AlAs heterostructures. |
| title | Theory of Coulomb driven nematicity in a multi-valley two-dimensional electron gas |
| topic | Strongly Correlated Electrons Mesoscale and Nanoscale Physics Statistical Mechanics |
| url | https://arxiv.org/abs/2406.12825 |