Observation of two relaxation mechanisms in transport between spin split edge states at high imbalance

TL;DR

This paper investigates two distinct long-time relaxation mechanisms in electron transport between spin-split edge states, revealing the role of dynamic nuclear polarization and nuclear spin diffusion through hysteresis and relaxation time measurements.

Contribution

It identifies and characterizes two different relaxation mechanisms with specific timescales in transport between spin-split edge states using a quasi-Corbino geometry.

Findings

Hysteresis observed in I-V curves indicates slow relaxation processes.

Two relaxation timescales of 25 s and 200 s were measured.

Long-time relaxation linked to nuclear polarization dynamics.

Abstract

Using a quasi-Corbino geometry to directly study electron transport between spin-split edge states, we find a pronounced hysteresis in the I-V curves, originating from slow relaxation processes. We attribute this long-time relaxation to the formation of a dynamic nuclear polarization near the sample edge. The determined characteristic relaxation times are 25 s and 200 s which points to the presence of two different relaxation mechanisms. The two time constants are ascribed to the formation of a local nuclear polarization due to flip-flop processes and the diffusion of nuclear spins.