The effect of film and interface structure on the transport properties of Heusler based current-perpendicular-to-plane spin valves

We present direct link between the transport properties of Co₂MnSi and Co₂FeMnSi Heusler based current-perpendicular-to-plane spin valves (CPP-SVs) and interface atomic structures resolved by aberration-corrected electron microscopy. The structure of the Co₂FeMnSi electrodes is L2₁ but their interface with the CoSi spacer is disordered. In contrast to the Co₂FeMnSi-electrodes, the Co₂MnSi-electrodes have abrupt interfaces with the Ag spacer though their ordering is not fully L2₁. The magnetoresistance of the Co₂MnSi-SV is over two orders of magnitude better than those of Co₂FeMnSi-SV, demonstrating that the atomic interface ordering is crucial for the enhancement of the magnetoresistance in the Heusler CPP-SVs.