Valley-dependent many-body effects in two-dimensional semiconductors

Abstract

We calculate the valley degeneracy $({g}_{v})$ dependence of the many-body renormalization of quasiparticle properties in multivalley two-dimensional (2D) semiconductor structures due to the Coulomb interaction between the carriers. Quite unexpectedly, the ${g}_{v}$ dependence of many-body effects is nontrivial and nongeneric, and depends qualitatively on the specific Fermi-liquid property under consideration. While the interacting 2D compressibility manifests monotonically increasing many-body renormalization with increasing ${g}_{v}$, the 2D spin susceptibility exhibits an interesting nonmonotonic ${g}_{v}$ dependence with the susceptibility increasing (decreasing) with ${g}_{v}$ for smaller (larger) values of ${g}_{v}$ with the renormalization effect peaking around ${g}_{v}\ensuremath{\sim}1--2$. Our theoretical results provide a clear conceptual understanding of recent valley-dependent 2D susceptibility measurements in AlAs quantum wells.