Spin relaxation anisotropy in a GaAs quantum dot

TL;DR

This study investigates the anisotropic spin relaxation times in a GaAs quantum dot, revealing deviations from circular dot predictions due to elliptical confinement and identifying the influence of Rashba and Dresselhaus spin-orbit interactions.

Contribution

It demonstrates how elliptical dot confinement affects spin relaxation anisotropy and provides experimental evidence of opposite signs of Rashba and Dresselhaus constants.

Findings

T1 varies by over an order of magnitude with magnetic field rotation.

Maximum T1 reaches about 80 ms at the magic angle.

Deviation from circular dot predictions due to elliptical potential.

Abstract

We report that the electron spin relaxation time, T1, in a GaAs quantum dot with a spin-1/2 ground state has a 180 degree periodicity in the orientation of the in-plane magnetic field. This periodicity has been predicted for circular dots as due to the interplay of Rashba and Dresselhaus spin orbit contributions. Different from this prediction, we find that the extrema in the T1 do not occur when the magnetic field is along the [110] and [1-10] crystallographic directions. This deviation is attributed to an elliptical dot confining potential. The T1 varies by more than an order of magnitude when rotating a 3 Tesla field, reaching about 80 ms for the magic angle. We infer from the data that in our device the sign of the Rashba and Dresselhaus constants are opposite.