Lithographically and electrically controlled strain effects on anisotropic magnetoresistance in (Ga,Mn)As

TL;DR

This study demonstrates that lithographic and electrical strain control significantly influences the anisotropic magnetoresistance in (Ga,Mn)As, revealing new effects and higher order terms that impact micromagnetic and transport properties.

Contribution

It shows that strain engineering can modulate crystalline AMR components and introduces new higher order terms in AMR phenomenology in (Ga,Mn)As.

Findings

Strain variations can produce crystalline AMR components larger than the unprocessed material.

Higher order terms in AMR expressions are observed.

Strain effects influence micromagnetic and magnetotransport properties.

Abstract

It has been demonstrated that magnetocrystalline anisotropies in (Ga,Mn)As are sensitive to lattice strains as small as 10^-4 and that strain can be controlled by lattice parameter engineering during growth, through post growth lithography, and electrically by bonding the (Ga,Mn)As sample to a piezoelectric transducer. In this work we show that analogous effects are observed in crystalline components of the anisotropic magnetoresistance (AMR). Lithographically or electrically induced strain variations can produce crystalline AMR components which are larger than the crystalline AMR and a significant fraction of the total AMR of the unprocessed (Ga,Mn)As material. In these experiments we also observe new higher order terms in the phenomenological AMR expressions and find that strain variation effects can play important role in the micromagnetic and magnetotransport characteristics of (Ga,Mn)As lateral nanoconstrictions.