Structural, electronic, and magnetic properties of the CoGa (0 0 1) surface and the L10 MnGa/CoGa interface: A density functional theory study

[Display omitted] •The most stable CoGa(0 0 1) surface is a clean Ga-terminated.•There are two stable MnGa/CoGa interface configurations.•The most stable interface configuration explains well the experimental results.•CoGa(0 0 1) surface has an induced ferromagnetic alignment. We have studied the CoGa(0 0 1) surface, and the formation of MnGa/CoGa interfaces using spin-polarized density functional theory. Our calculations are motivated by a recent experimental report of a MnGa/CoGa magnetic interface used in the construction of a magnetic tunnel junction. For the CoGa(0 0 1) surface we have considered several models with different periodicities. Using the surface energy formalism, it is found that the most stable configuration is an ideal Ga terminated surface. Two different configurations were found for the interfaces: for Co rich growth conditions a Mn/Co interface is formed, while for most of the allowed growth condition, a Mn/Ga/Co is the most stable. The latter makes perfect match with the experimentally proposed interface arrangement. For the stable structures, we have studied their structural, electronic, and magnetic properties. We have found that the CoGa surface has an induced magnetism due to the Ga surface atoms. In the case of the interfaces, we have found that Mn has a strong effect on the substrate for the Mn/Co interface, but it barely affects the Mn/Ga/Co interface.