Spontaneous Emergence of Persistent Spin Helix from Homogeneous Spin Polarization

TL;DR

This paper shows that in one-dimensional structures with spin-orbit coupling, a uniform spin polarization naturally evolves into a stable spin helix, with potential for tunable spin structures in nano-devices.

Contribution

It introduces a novel heat-equation mapping approach to analyze the spontaneous formation of persistent spin helices from homogeneous spin states.

Findings

Homogeneous spin polarization decays into a persistent spin helix in 1D structures.

The method allows tuning spin structures via spin-orbit strength and structure length.

Predicts formation of persistent spin helix in 2D channels from uniform polarization.

Abstract

We demonstrate that a homogeneous spin polarization in one-dimensional structures of finite length in the presence of Bychkov-Rashba spin-orbit coupling decays spontaneously toward a persistent spin helix. The analysis of formation of spin helical state is presented within a novel approach based on a mapping of spin drift-diffusion equations into a heat equation for a complex field. Such a strikingly different and simple method allows generating robust spin structures whose properties can be tuned by the strength of the spin orbit interaction and/or structure's length. We generalize our results for two-dimensional case predicting formation of persistent spin helix in two-dimensional channels from homogeneous spin polarization.