Electronic inhomogeneity at magnetic domain walls in strongly-correlated systems

TL;DR

This paper demonstrates that nano-scale variations at magnetic domain walls in strongly-correlated systems can create insulating regions affecting electronic transport, with implications for magnetic device technology.

Contribution

It introduces a Landau-Ginzburg model showing how spin gradients induce insulating antiferromagnetic cores at domain walls in metallic ferromagnets.

Findings

Domain walls can host insulating antiferromagnetic regions.

Charge transport is significantly affected by these inhomogeneous walls.

Results explain experimental observations in colossal magnetoresistance materials.

Abstract

We show that nano-scale variations of the order parameter in strongly-correlated systems can induce local spatial regions such as domain walls that exhibit electronic properties representative of a different, but nearby, part of the phase diagram. This is done by means of a Landau-Ginzburg analysis of a metallic ferromagnetic system near an antiferromagnetic phase boundary. The strong spin gradients at a wall between domains of different spin orientation drive the formation of a new type of domain wall, where the central core is an insulating antiferromagnet, and connects two metallic ferromagnetic domains. We calculate the charge transport properties of this wall, and find that its resistance is large enough to account for recent experimental results in colossal magnetoresistance materials. The technological implications of this finding for switchable magnetic media are discussed.