Domain wall dynamics in soft magnetic materials

TL;DR

This paper investigates the critical dynamics of domain walls in magnetostrictive materials, deriving exact expressions for velocity and susceptibility, and analyzing the effects of demagnetization and disorder.

Contribution

It provides a theoretical framework with exact solutions for domain wall motion considering long-range effects and quenched disorder, extending understanding of critical phenomena in magnetic systems.

Findings

System is critical when demagnetization constant and velocity vanish

Derived critical exponents to order 4-d

Predictions agree with simulations and Barkhausen noise data

Abstract

The dynamics of a domain wall in magnetostrictive materials is investigated. The domain wall is modeled by a d-dimensional interface moving in a d+1-dimensional environment. Long-range demagnetization effects and quenched disorder are considered, while the external magnetic field is increased at constant rate. Exact expressions for the average interface velocity and susceptibility are obtained, resulting that the system is critical when the demagnetization constant and the average interface velocity vanishes. The critical exponents are computed to O(4-d). Our predictions are compared with numerical simulations and Barkhausen noise measurements reported in the literature.