Very large magnetoresistance in lateral ferromagnetic (ga, mn)as wires with nanoconstrictions

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 [Formula presented], 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 [Formula presented]. © 2003 The American Physical Society.