Spin-relaxation anisotropy in a nanowire quantum dot with strong spin-orbit coupling

Zhi-Hai Liu,Rui Li

doi:10.1063/1.5030970

Abstract

We study the impacts of the magnetic field direction on the spin-manipulation and the spin-relaxation in a one-dimensional quantum dot with strong spin-orbit coupling. The energy spectrum and the corresponding eigenfunctions in the quantum dot are obtained exactly. We find that no matter how large the spin-orbit coupling is, the electric-dipole spin transition rate as a function of the magnetic field direction always has a π periodicity. However, the phonon-induced spin relaxation rate as a function of the magnetic field direction has a π periodicity only in the weak spin-orbit coupling regime, and the periodicity is prolonged to 2π in the strong spin-orbit coupling regime.

Highlights

In recent decades, the spin-orbit couling (SOC) in III-V semiconductor materials has promoted great advances in the studies of spintronics
There are two kinds of SOCs in III-V semiconductor materials: the Dresselhaus SOC generated by the bulk inversion asymmetry and the Rashba SOC induced by the structure inversion asymmetry.[19,20,21]
The electric-dipole spin resonant (EDSR) and the phonon-induced spin relaxation are studied in details with specific interest focused on the interplay between the SOC and the magnetic field direction

Summary

INTRODUCTION

The spin-orbit couling (SOC) in III-V semiconductor materials has promoted great advances in the studies of spintronics. In order to observe the nontrivial SOC effect one should first break the time-reversal symmetry by applying an external magnetic field.[10,18] In the presence of both the magnetic field and the SOC, only a few models are exact solvable. In all of the above models, the magnetic field direction is fixed From both the theoretical and the experimental viewpoints, the magnetic field direction plays an important role for the observable SOC effect in quantum dot.[8,9,10,11,28,29,30,31,32,33] It is desirable to clarify the influences of the magnetic field direction on the spin properties when SOC is strong. While for the phonon-induced spin relaxation rate,[35] with the increase of the SOC, the periodicity of the relaxation rate changes from π in the weak SOC regime to 2π in the strong SOC regime

THE MODEL

THE ENERGY SPECTRUM AND THE WAVE FUNCTIONS

ELECTRIC-DIPOLE SPIN RESONANCE

THE PHONON-INDUCED SPIN RELAXATION

CONCLUSION