Radial Spin Helix in Two-Dimensional Electron Systems with Rashba Spin-Orbit Coupling

TL;DR

This paper introduces the concept of a radial spin helix in 2D electron systems with Rashba spin-orbit coupling, demonstrating its prolonged relaxation time and potential for stable spin polarization structures.

Contribution

It derives a system of equations for spin polarization density and shows that the radial spin helix relaxes slower than other spin configurations, highlighting its stability.

Findings

Radial spin helix relaxes slower than homogeneous and plain spin helix.

Spin polarization at the center remains nearly unchanged at short times.

Relaxation time of the radial spin helix matches that of plain spin helix at longer times.

Abstract

We suggest a long-lived spin polarization structure, a radial spin helix, and study its relaxation dynamics. For this purpose, starting with a simple and physically clear consideration of spin transport, we derive a system of equations for spin polarization density and find its general solution in the axially symmetric case. It is demonstrated that the radial spin helix of a certain period relaxes slower than homogeneous spin polarization and plain spin helix. Importantly, the spin polarization at the center of the radial spin helix stays almost unchanged at short times. At longer times, when the initial non-exponential relaxation region ends, the relaxation of the radial spin helix occurs with the same time constant as that describing the relaxation of the plain spin helix.