Effects of the interfacial states on the spin-dependent tunneling of Mn3Al-based magnetic tunnel junction

Abstract

The study of antiferromagnets (AFMs) has become one of the hotspots of spintronics because of their strong environmental adaptability; however, their magnetic ordering structure limits their practical application. The compensated ferrimagnet Mn3Al has the characteristics of an AFM and the magnetic moment can be controlled by a magnetic field. The successful synthesis of Mn3Al, which possesses a high Curie temperature (605 K), may lead to new applications in spintronics devices. In this work, the electronic structure of free Mn3Al (001) surfaces and the interface effects of the Mn3Al electrode and the GaAs tunnel barrier in the magnetic tunnel junction (MTJ) are investigated with the non-equilibrium Green’s function method. Although redistribution of the partial density of states between the surface and bulk is observed for the two different types of Mn3Al surfaces, the half-metallicity is retained for both the surface structures. Due to the half-metallicity of the surfaces, the tunneling magnetoresistance (TMR) of the MTJ reaches up to 107%. Moreover, the TMR dependence on the GaAs barrier thickness as well as the interface is studied. Through the visual display of the interface states, we find that the interface states can promote electron tunneling in the antiparallel configuration. The high TMR can be maintained at a small barrier width owing to the weak interface states. The results are explained with the transmission coefficient in reciprocal space. This work provides some physical insight for the design and implementation of Mn3Al-based MTJs.