Very large magnetoresistance in lateral ferromagnetic (Ga,Mn)As wires with nanoconstrictions

TL;DR

This study demonstrates significant magnetoresistance effects in (Ga,Mn)As nanostructures with nanoconstrictions, highlighting the role of domain-wall trapping and spin accumulation in these ferromagnetic semiconductor devices.

Contribution

The paper reports the fabrication and characterization of (Ga,Mn)As nanostructures with nanoconstrictions, revealing large magnetoresistance effects due to domain-wall trapping and tunnel barriers.

Findings

Magnetoresistance up to 8% in metallic samples

Magnetoresistance up to 2000% in tunnel barrier samples

Controlled switching of magnetization states via shape anisotropy

Abstract

We have fabricated (Ga,Mn)As nanostructures in which domain walls can be pinned by sub-10 nm constrictions. Controlled by shape anisotropy, we can switch the regions on either side of the constriction to either parallel or antiparallel magnetization. All samples exhibit a positive magnetoresistance, consistent with domain-wall trapping. For metallic samples we find a magnetoresistance up to 8%, which can be understood from spin accumulation. In samples where, due to depletion at the constriction, a tunnel barrier is formed, we observe a magnetoresistance of up to 2000 %.