Ab-initio investigation of the interfacial structural, electronic, and magnetic properties of Co$_{2}$MnAl/X (X = MgO and GaAs) heterostructures

The structural, electronic, and magnetic properties of (100)-oriented Co$_{2}$MnAl/MgO and Co$_{2}$MnAl/GaAs heterostructures are investigated using plane-wave pseudopotential density functional theory. For the Co$_{2}$MnAl/MgO, CoCo-MgMg, CoCo-OO, MnAl-MgMg, and MnAl-OO interfaces in top-to-top configurations are studied, while for Co$_{2}$MnAl/GaAs, both top-to-top (Co-Ga, Co-As, Mn-Ga, Mn-As, Al-Ga, Al-As) and bridge-site (CoCo-Ga, CoCo-As, MnAl-Ga, MnAl-As) interfaces are considered. The interfacial geometries featuring Co- or CoCo-atomic terminations for the Co2MnAl slab exhibit larger adhesion energies compared to those terminated with Mn-, Al-, or MnAl-atomic terminations. This indicates their greater interfacial stability. In contrast, MnAl-, Mn-, or Al-terminated interfaces preserve near half-metallicity, whereas Co- and CoCo-terminated geometries display a strongly metallic character. All studied interfaces show enhanced magnetic moments relative to their bulk counterparts, primarily arising from interfacial atoms and their nearest neighbours. These findings offer valuable insights for optimizing Co2MnAl-based heterostructures in spintronic applications.