Suppressed decay of a laterally confined persistent spin helix

TL;DR

This study experimentally examines how lateral confinement in GaAs wire structures affects the lifetime and dynamics of persistent spin helices, revealing partial suppression of spin decay due to one-dimensional diffusion effects.

Contribution

It provides the first detailed experimental analysis of persistent spin helix behavior in etched wire structures with varying widths, highlighting the impact of lateral confinement on spin dynamics.

Findings

Spin polarization is strongly enhanced in narrow wires due to one-dimensional diffusion.

The intrinsic lifetime of the spin helix is only weakly increased by confinement.

Lateral confinement partially suppresses the cubic Dresselhaus spin-orbit interaction.

Abstract

We experimentally investigate the dynamics of a persistent spin helix in etched GaAs wire structures of 2 to 80 um width. Using magneto-optical Kerr rotation with high spatial resolution, we determine the lifetime of the spin helix. A few nanoseconds after locally injecting spin polarization into the wire, the polarization is strongly enhanced as compared to the two-dimensional case. This is mostly attributed to a transition to one-dimensional diffusion, strongly suppressing diffusive dilution of spin polarization. The intrinsic lifetime of the helical mode is only weakly increased, which indicates that the channel confinement can only partially suppress the cubic Dresselhaus spin-orbit interaction.