Structure, magnetism, and electronic properties of inverse Heusler alloy Ti2CoAl/MgO(100) herterojuction: The role of interfaces

Abstract

In this study, the interface structures, atom-resolved magnetism, density of states, and spin polarization of 10 possible atomic terminations in the Ti2CoAl/MgO(100) heterojunction were comprehensively investigated using first-principle calculations. In the equilibrium interface structures, the length of the alloy-Mg bond was found to be much longer than that of the alloy-O bond because of the forceful repulsion interactions between theHeusler interface atoms andMg atoms. The competition among d-electronic hybridization, d-electronic localization, and the moving effect of the interface metal atoms played an important role in the interface atomic magnetic moment. Unexpected interface states appeared in the half-metallic gap for all terminations. The "ideal" half-metallicity observed in the bulk had been destroyed. In TiAl-Mg and AlAl-O terminations, the maximal spin polarization of about 65% could be reserved. The tunnel magnetoresistance (TMR) value was deduced to be lower than 150% in the Ti2CoAl/MgO(100) heterojunction at low temperature.