Nonmonotonic Temperature-dependent Resistance in Low Density 2D Hole Gases

TL;DR

This study investigates the temperature-dependent resistance in low-density 2D hole gases in GaAs/AlGaAs quantum wells, revealing a nonmonotonic behavior and a fundamental relationship between scattering mechanisms at different temperatures.

Contribution

It uncovers a nonmonotonic temperature dependence of resistance and identifies a universal resistance form independent of density in 2D hole gases.

Findings

Resistance exhibits nonmonotonic temperature dependence.

Resistance follows an exponential form at low T and a 1/T decay at higher T.

The resistance form is density-independent, indicating fundamental scattering mechanisms.

Abstract

The low temperature longitudinal resistance-per-square Rxx(T) in ungated GaAs/AlGaAs quantum wells of high peak hole mobility 1.7x10^6 cm^2/Vs is metallic for 2D hole density p as low as 3.8x10^9 cm-2. The electronic contribution to the resistance, R_{el}(T), is a nonmonotonic function of T, exhibiting thermal activation, R_{el}(T) ~ exp{-E_a/kT}, for kT<<E_F and a heretofore unnoted decay R_{el}(T) ~ 1/T for k_T>EF. The form of R_{el}(T) is independent of density, indicating a fundamental relationship between the low and high T scattering mechanisms in the metallic state.