Magnetoresistance of individual ferromagnetic GaAs/(Ga,Mn)As core-shell nanowires

TL;DR

This study examines the angle-dependent magnetoresistance of individual ferromagnetic GaAs/(Ga,Mn)As core-shell nanowires at cryogenic temperatures, revealing strong anisotropies linked to magnetic effects and anisotropy fields.

Contribution

It provides a detailed analysis of the magnetoresistance behavior in ferromagnetic nanowires, highlighting the dominant uniaxial anisotropy and its quantitative description using effective magnetic field concepts.

Findings

Strong uniaxial anisotropy along wire axis

Magnetoresistance described by effective magnetic field model

Anisotropy larger than in lithographically prepared stripes

Abstract

We investigate, angle dependent, the magnetoresistance (MR) of individual self-assembled ferromagnetic GaAs/(Ga,Mn)As core-shell nanowires at cryogenic temperatures. The shape of the MR traces and the observed strong anisotropies in transport can be ascribed to the interplay of the negative magnetoresistance effect and a strong uniaxial anisotropy with the magnetic easy direction pointing along the wire axis. The magnetoresistance can be well described by a quantitative analysis based on the concept of the effective magnetic field, usually used to describe ferromagnetic resonance phenomena. The nanowires we investigate exhibit a uniaxial anisotropy which is approximately 5 times larger than the strain induced anisotropy observed in lithographically prepared (Ga,Mn)As stripes.