Anomalous spin-orbit effects in a strained InGaAs/InP quantum well structure

TL;DR

This study investigates spin-orbit effects in a strained InGaAs/InP quantum well, revealing non-monotonic dependence of spin-orbit relaxation time on gate voltage and identifying strain-related asymmetry as a key factor.

Contribution

It provides new insights into spin-orbit scattering behavior in strained quantum wells, highlighting effects beyond Rashba and Dresselhaus mechanisms.

Findings

Spin-orbit relaxation time varies non-monotonically with gate voltage.

Maximum spin-orbit scattering rate observed at specific electron density.

Strain and interface asymmetry influence spin-orbit effects.

Abstract

There currently is a large effort to explore spin-orbit effects in semiconductor structures with the ultimate goal of manipulating electron spins with gates. A search for materials with large spin-orbit coupling is therefore important. We report results of a study of spin-orbit effects in a strained InGaAs/InP quantum well. The spin-orbit relaxation time, determined from the weak antilocalization effect, was found to depend non-monotonically on gate voltage. The spin orbit scattering rate had a maximum value of $5\times 10^{10}s^{-1}$ at an electron density of $n=3\times 10^{15} m^{-2}$. The scattering rate decreased from this for both increasing and decreasing densities. The smallest measured value was approximately $10^9 s^{-1}$ at an electron concentration of $n=6\times 10^{15} m^{-2}$. This behavior could not be explained by either the Rashba nor the bulk Dresselhaus mechanisms but is attributed to asymmetry or strain effects at dissimilar quantum well interfaces.