The Anthony J Leggett Institute for Condensed Matter Physics Special Seminar: "Theory of Coulomb driven nematicity in a multi-valley two-dimensional electron gas"
- Sponsor
- Physics Department
- Speaker
- Erez Berg, Weizmann Institute of Science
- Contact
- Ljubica Milutinovic
- ljubicam@illinois.edu
- Phone
- 217-300-6393
- Views
- 175
- Originating Calendar
- Physics - The Anthony J Leggett Institute for Condensed Matter Theory Seminar
The properties of a two-dimensional electron gas (2DEG) in a semiconductor host with two valleys related by an underlying C4 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.