Cubic Dresselhaus Spin-Orbit Coupling in 2D Electron Quantum Dots

TL;DR

This paper investigates the impact of cubic Dresselhaus spin-orbit coupling in GaAs/AlGaAs quantum dots, revealing its significant role in spin-flip processes and providing a more accurate estimate of the coupling constant from experimental data.

Contribution

It introduces a semiclassical billiard model to quantify cubic Dresselhaus effects and refines the value of the coupling constant based on experimental conductance measurements.

Findings

Cubic Dresselhaus coupling constant is approximately 9 eVA^3

Majority of spin-flip spin-orbit effects originate from cubic Dresselhaus term

Significantly lower coupling constant than previously cited

Abstract

We study effects of the oft-neglected cubic Dresselhaus spin-orbit coupling (i.e., $\propto p^3$) in GaAs/AlGaAs quantum dots. Using a semiclassical billiard model, we estimate the magnitude of the spin-orbit induced avoided crossings in a closed quantum dot in a Zeeman field. Using these results, together with previous analyses based on random matrix theory, we calculate corresponding effects on the conductance through an open quantum dot. Combining our results with an experiment on conductance through an 8 um^2 quantum dot [D M Zumbuhl et al., Phys. Rev. B 72, 081305 (2005)] suggests that 1) the GaAs Dresselhaus coupling constant, $\gamma$, is approximately 9 eVA^3, significantly less than the commonly cited value of 27.5 eVA^3 and 2) the majority of the spin-flip component of spin-orbit coupling can come from the cubic Dresselhaus term.