Magnetoresistance of spin valve structures based on the full Heusler alloy Co2MnSi

Co2MnSi∕Cu∕Co pseudo-spin-valves (PSVs) have been grown by dc magnetron sputtering from elemental targets onto GaAs(001). The stoichiometric Heusler layer was highly textured, following the [001] orientation of the lattice matched GaAs(001). Hysteresis loops showed independent switching of the magnetization of the two ferromagnetic layers. Transport measurements of the samples were performed in both the current in plane (CIP) and current perpendicular to plane (CPP) geometries. Clear low-field spin valve contributions were observed at 15K for the CIP PSV, a conventionally patterned mesa CPP device and a CPP device fabricated in the focused ion beam microscope. Analysis of the CPP data did not show the half-metallic behavior of Co2MnSi as expected from theory.