Valley dependent many-body effects in 2D semiconductors

TL;DR

This paper investigates how valley degeneracy affects many-body quasiparticle properties in 2D semiconductors, revealing complex, property-dependent behaviors that explain recent experimental observations.

Contribution

It provides a theoretical analysis of valley-dependent many-body effects in 2D semiconductors, highlighting nontrivial and property-specific dependencies on valley degeneracy.

Findings

Compressibility increases monotonically with valley degeneracy.

Spin susceptibility shows non-monotonic dependence on valley degeneracy.

Results explain recent experimental measurements in AlAs quantum wells.

Abstract

We calculate the valley degeneracy ($g_v$) dependence of the many-body renormalization of quasiparticle properties in multivalley 2D semiconductor structures due to the Coulomb interaction between the carriers. Quite unexpectedly, the $g_v$ dependence of many-body effects is nontrivial and non-generic, 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 non-monotonic $g_v$ dependence with the susceptibility increasing (decreasing) with $g_v$ for smaller (larger) values of $g_v$ with the renormalization effect peaking around $g_v\sim 1-2$. Our theoretical results provide a clear conceptual understanding of recent valley-dependent 2D susceptibility measurements in AlAs quantum wells.