Modification of magnetotransport properties across patterned GaMnAs nanoconstrictions by application of high current densities

We report on modifications in the magnetotransport properties across patterned GaMnAs nanoconstrictions by the application of high current densities (< 10⁷ A/ cm²). Initially, we observe controllable changes in the electrical resistance with the direction of the bias current. Repeated biases at high current densities greatly increase the constriction resistances. Subsequent biasing and magnetotransport measurements show nearly a fourfold increase in the magnetoresistances and large changes in the magnetic switching behavior of GaMnAs. The initial reversibility of the changes in resistance suggests that dopant electromigration may locally alter the interstitial concentrations of Mn at the nanoconstriction.