Spin transition rates in nanowire superlattices: Rashba spin-orbit coupling effects

TL;DR

This paper explores how Rashba spin-orbit coupling affects spin transition rates in nanowire superlattices, revealing level crossings, large anticrossings, and the influence of phonons and electromagnetic fields on spin dynamics.

Contribution

It provides a detailed analysis of spin transition mechanisms in nanowire superlattices considering Rashba coupling, including exact transition probabilities and effects of wave vector variations.

Findings

Rashba coupling induces level crossing points in nanowire superlattices.

Phonon-mediated spin transitions are significantly faster than electromagnetic field-mediated ones.

Transition probabilities can be tuned to resonance or exhibit damping depending on wave vector and coupling strength.

Abstract

We investigate the influence of Rashba spin-orbit coupling in a parabolic nanowire modulated by longitudinal periodic potential. The modulation potential can be obtained from realistically grown supperlattices (SLs). Our study shows that the Rashba spin-orbit interaction induces the level crossing point in the parabolic nanowire SLs. We estimate large anticrossing width (approximately 117 $\mu eV$) between singlet-triplet states. We study the phonon and electromagnetic field mediated spin transition rates in the parabolic nanowire SLs. We report that the phonon mediated spin transition rate is several order of magnitude larger than the electromagnetic field mediated spin transition rate. Based on the Feynman disentangling technique, we find the exact spin transition probability. For the case wave vector $k=0$, we report that the transition probability can be tuned in the form of resonance at fixed time interval. For the general case ($k\neq 0$), we solve the Riccati equation and find that the arbitrary values of $k$ induces the damping in the transition probability. At large value of Rashba spin-orbit coupling coefficients for ($k\neq 0$), spin transition probability freezes.