Effective mass enhancement in two-dimensional electron systems: the role of interaction and disorder effects

TL;DR

This paper investigates how electron-electron interactions and disorder influence the effective mass in two-dimensional electron systems, revealing a sharp increase in effective mass at low densities through many-body calculations.

Contribution

It introduces a detailed many-body theoretical approach using the $GW\Gamma$ approximation to analyze effective mass enhancement considering interaction and disorder effects.

Findings

Effective mass sharply increases as electron density decreases.

Disorder from charged impurities significantly affects the effective mass behavior.

Theoretical results align with recent experimental observations.

Abstract

Recent experiments on two-dimensional (2D) electron systems have found a sharp increase in the effective mass of electrons with decreasing electron density. In an effort to understand this behavior we employ the many-body theory to calculate the quasiparticle effective mass in 2D electron systems. Because the low density regime is explored in the experiments we use the $GW\Gamma$ approximation where the vertex correction $\Gamma$ describes the correlation effects to calculate the self-energy from which the effective mass is obtained. We find that the quasiparticle effective mass shows a sharp increase with decreasing electron density. Disorder effects due to charged impurity scattering plays a crucial role in density dependence of effective mass.