Formation of ferromagnetic/ferrimagnetic epitaxial interfaces: Stability and magnetic properties.

We have studied the formation of epitaxial ferromagnetic/ferrimagnetic MnGa(0 0 1)/Mn 4 N(0 0 1) heterostructures by using spin polarized first principles calculations. In particular, we have analyzed the stability of the surface and interface as function of the N content. Since the Mn 4 N(0 0 1) has two stable surface terminations with a (1 × 1) periodicity, we have used them as substrates to grow MnGa. The interface formation energy formalism has been applied to describe the stability of all proposed models. Our calculations show that Mn at the interface is energetically favorable. Moreover, stability of the MnGa surface has a direct nitrogen dependence. Specifically, without extra N, the Ga-terminated surface is stable in the whole range of chemical potential for both substrates. Once N is added to the surface, the MnN-terminated surface becomes stable in both substrates for different ranges of chemical potential. Although MnGa and Mn 4 N are not antiferromagnetic materials, they form a local antiferromagnetic-like arrangement at the interface. This thermodynamically stable system could have potential applications in the construction of new generation spintronic devices. [ABSTRACT FROM AUTHOR]