Magnetic and transport properties of Mn3−xGa/MgO/Mn3−xGa (0 ≤ x ≤ 1) magnetic tunnel junctions are studied using first-principles approach based on density functional theory and non-equilibrium Green’s function. Perpendicular magnetization, of which the magnetic anisotropy energy reaches more than 1 meV/unit-cell, is confirmed to be energetically favoured by both Mn2Ga and Mn3Ga thin films. Furthermore, despite high spin-polarization at the Fermi energy for both these compounds as reported, our transport calculation shows considerable disparity in the transmission behaviour between Mn2Ga/MgO/Mn2Ga(001) and Mn3Ga/MgO/Mn3Ga(001) magnetic tunnel junctions: huge optimistic tunneling magnetoresistance ratio of 103% for the former, and nevertheless, no tunneling magnetoresistance effect absolutely for the latter. This phenomenon is attributed to the symmetry selective filtering effect of the MgO spacer. On this premise, Mn3−xGa compounds with low Mn concentration are predicted to be promising candidate materials to serve as the electrodes of spin-transfer torque devices in the next-generation data storage technique.

We present results of the magnetic, structural and chemical characterizations

Transport properties of giant magnetoresistance (MR) junction consisting of trilayer Co2CrSi/Cu2CrAl/Co2CrSi Heusler alloys (L21) are studied using first-principles approach based on density functional theory and the non-equilibrium Green's function method. Highly conductive channels are found in almost the entire k-plane when the magnetizations of the electrodes are parallel, while they are completely blocked in the antiparallel configuration, which leads to a high magnetoresistance ratio (the pessimistic MR ratio is nearly 100%). Furthermore, the calculated I-V curve shows that the device behaves as a good spin valve with a considerable disparity in currents under the parallel and antiparallel magnetic configurations of the electrodes. The Co2CrSi/Cu2CrAl/Co2CrSi junction could be useful for high-performance all-metallic current-perpendicular-to-plane giant magnetoresistance reading head for the next generation high density magnetic storage.