Crossover in the Structure Between Bloch and Linear Domain Walls

TL;DR

This paper investigates the transition of domain wall structures from Bloch to linear types near the Curie temperature, revealing implications for magnetoresistance in nanowires.

Contribution

It introduces a detailed analysis of the crossover in domain wall structures and its impact on electron spin mistracking and magnetoresistance.

Findings

Domain wall structure shifts from Bloch to linear near Curie temperature.

The linear wall has a diminished magnetization magnitude at its center.

This transition affects electron spin dynamics and magnetoresistance.

Abstract

Near the Curie temperature of a ferromagnet the form of a domain wall changes from the Bloch type to (asymptotically) the linear Zhirnov wall. Unlike the simple 180 degree rotation of the magnetization vector in a Bloch wall, its absolute value diminishes near the center of the wall. This leads to a decrease of the total transverse component of the exchange field inside the wall and to an increase of mistracking of the spins of the electrons traversing the wall. This mechanism may help explain large magnetoresistance of domain walls in thin nanowires, as the Curie temperatures of low-dimensional nanostructures are known to be lower than in bulk ferromagnets while the anisotropy energy stays virtually unchanged.