Epitaxially grown MnAs∕GaAs lateral spin valves

Abstract

The authors report magnetoresistance of lateral spin valves fabricated from an epitaxially grown $\mathrm{Mn}\mathrm{As}∕\mathrm{Ga}\mathrm{As}$ heterostructure and utilizing a Schottky tunnel barrier for efficient spin injection. A coercive field difference between the two ferromagnetic MnAs contacts is obtained by a difference in aspect ratio. Peak magnetoresistances of 3.6% at $10\mathrm{K}$ and 1.1% at $125\mathrm{K}$ are measured for a $0.5\mu \mathrm{m}$ channel length spin valve. The authors observe an exponential decay of the peak magnetoresistance with increasing channel length, which is indicative of diffusive spin transport. The magnetoresistance increases with increasing bias and with decreasing temperature. Control experiments have been carried out to confirm the spin-valve effect.