Interaction Effects in Conductivity of a Two-Valley Electron System in High-Mobility Si Inversion Layers

TL;DR

This study measures the conductivity of high-mobility Si MOSFETs across various densities, temperatures, and magnetic fields, confirming interaction effect theories in disordered 2D electron systems and analyzing valley effects.

Contribution

It provides experimental validation of interaction effects theory in a two-valley 2D electron system, including measurements of key parameters like valley splitting and scattering times.

Findings

Conductivity increases quasi-linearly with decreasing temperature down to ~0.4K.

Conductivity shows a downturn at lower temperatures, consistent with theory.

Fermi-liquid parameters agree with those from Shubnikov-de Haas oscillation analysis.

Abstract

We have measured the conductivity of high-mobility (001) Si metal-oxide-semiconductor field effect transistors (MOSFETs) over wide ranges of electron densities n=(1.8-15)x10^11cm^2, temperatures T=30mK-4.2K, and in-plane magnetic fields B=0-5T. The experimental data have been analyzed using the theory of interaction effects in the conductivity of disordered 2D systems. The parameters essential for comparison with the theory, such as the intervalley scattering time and valley splitting, have been measured or evaluated in independent experiments. The observed behavior of the conductivity, including its quasi-linear increase with decreasing T down to ~0.4K and its downturn at lower temperatures, is in agreement with the theory. The values of the Fermi- liquid parameter obtained from the comparison agree with the corresponding values extracted from the analysis of Shubnikov-de Haas oscillations based on the theory of magnetooscillations in interacting 2D systems.