High-performance giant-magnetoresistance junction with B2-disordered Heusler alloy based Co2MnAl/Ag/Co2MnAl trilayer

The current-perpendicular-to-plane giant magnetoresistance (MR) devices with full-Heulser Co2MnAl (CMA) electrodes and a Ag spacer have been simulated to investigate the relationship between the transport properties and the structural disordering of electrodes by performing first-principles electronic structure and ballistic transport calculations. The CMA electrode has nearly negligible interfacial roughness in both L21 and B2-types. The transmission coefficient Tσ(E,k→//) is found strongly dependent on the structures of the trilayers for different structural CMA electrodes. High majority-spin electron conductance in the magnetization parallel configuration turns up in the entire k→-plane and the MR ratio reaches as high as over 90% for the B2-based CMA/Ag/CMA magnetic trilayers. In contrast, the L21-based one has ∼60% MR ratio resulting from much lower bulk spin-asymmetry coefficient (β), which might be caused by the vibrational spin-polarization in each atomic layer adjacent to the interfaces in the corresponding model. The patterns of Tσ(E,k→//) indicates that B2-based CMA/Ag/CMA magnetic trilayers are promising giant magnetoresistance junctions with high performance.