Domain Wall Motion in the Presence of Nuclear Spins

TL;DR

This paper studies how nuclear spins influence domain wall motion, revealing that nuclear spin fluctuations create a complex, stochastic potential landscape affecting relaxation times, especially at high temperatures.

Contribution

It introduces a model for domain wall dynamics influenced by nuclear spins, highlighting the impact of nuclear spin fluctuations on relaxation time distributions.

Findings

Nuclear spins create a random potential landscape for domain walls.

Relaxation times exhibit long-tailed distributions due to rare nuclear spin fluctuations.

The effects are significant in both thermal and quantum regimes.

Abstract

We investigate the motion of a domain wall in the presence of a dynamical hyperfine field. At temperature T high compared to the hyperfine coupling, the nuclear spins create a spatially random potential landscape, with dynamics dictated by the nuclear relaxation time $T_2$. The distribution of the domain wall relaxation times (both in the thermal and quantum regimes) can show a long tail, characteristic of stochastic processes where rare events are important. Here, these are due to occasional strong fluctuations in the nuclear spin polarisation.