Current induced magnetization reversal in spin valves with Heusler alloys

Abstract Current induced magnetization reversal using current-perpendicular-to-plane (CPP) spin valves devises with Co 2 MnGe, Co 2 FeSi, and Co 75 Fe 25 alloys were investigated. Film stacks of Si/SiO 2 /Cu/IrMn/Heusler-pinned-layer/Cu/Heusler-free-layer were deposited by DC magnetron sputtering followed by post-annealing. Saturation magnetization ( B s ) of Co 2 MnGe, Co 2 FeSi, and Co 75 Fe 25 are 12.7, 14.0, and 25 kg, respectively and magnetoresistance (MR) ratios of spin valves with the Co 2 MnGe, Co 2 FeSi, and Co 75 Fe 25 are 3.6%, 3.5%, and 2.2%, respectively. The B s values and MR ratios obtained for Co 2 MnGe and Co 2 FeSi spin valves were smaller and larger, respectively, than those obtained for Co 75 Fe 25 . We speculated that the large MR ratios could be attributed to larger spin polarization of Heusler alloys. J c0 of Co 2 MnGe, Co 2 FeSi, and Co 75 Fe 25 spin valves were 1.6×10 7 , 2.7×10 7 , and 5.1×10 7 A/cm 2 , respectively. The thermal factors of Co 2 MnGe, Co 2 FeSi, and Co 75 Fe 25 were 65, 48, and 55, respectively. Using the Heusler alloys, we successfully reduced the intrinsic critical current without degrading the thermal factor.