IrCrMnZ (Z = Al, Ga, Si, Ge) Heusler alloys as electrode materials for MgO-based magnetic tunneling junctions: a first-principles study

We study IrCrMnZ (Z = Al, Ga, Si, Ge) systems using first-principles calculations from the perspective of their application as electrode materials of MgO-based magnetic tunnel junctions (MTJs). These materials have highly spin-polarized conduction electrons with a partially occupied Delta(1) band, which is important for coherent tunneling in a parallel magnetization configuration. The Curie temperatures of IrCrMnAl and IrCrMnGa are very high (above 1300 K), as predicted from mean-field-approximation. The stability of the ordered phase against various antisite disorders is investigated. We discuss here the effect of 'spin-orbit-coupling' on the electronic structure around the Fermi level. Further, we investigate the electronic structure of the IrCrMnZ/MgO heterojunction along the (001) direction. IrCrMnAl/MgO and IrCrMnGa/MgO maintain half-metallicity even at the MgO interface, with no interfacial states at/around the Fermi level in the minority-spin channel. Large majority-spin conductance of IrCrMnAl/MgO/IrCrMnAl and IrCrMnGa/MgO/IrCrMnGa is reported from the calculation of the ballistic spin-transport property for the parallel magnetization configuration. We propose IrCrMnAl/MgO/IrCrMnAl and IrCrMnGa/MgO/IrCrMnGa as promising MTJs with a weaker temperature dependence of tunneling magnetoresistance ratio, owing to their very high Curie temperatures.

Automated summary

In this study, the IrCrMnZ systems were investigated for their potential application as electrode materials in MgO-based magnetic tunnel junctions (MTJs). IrCrMnAl and IrCrMnGa were found to have very high Curie temperatures and stable ordered phases. The influence of spin-orbit coupling on electronic structure and the electronic structure of IrCrMnZ/MgO heterojunction were discussed. Additionally, it was observed that IrCrMnAl/MgO and IrCrMnGa/MgO maintained half-metallicity even at the interface, showing promising characteristics for MTJs with a weaker temperature dependence.