Structural stability and the electronic and magnetic properties of ferrimagnetic Mn4N(0 0 1) surfaces

Abstract

We have carried out spin-polarized first principles calculations to describe the surface stability and the electronic and magnetic properties of Mn4N(001) surfaces. Results show two different surface terminations with different N content. The surface formation energies indicate that for manganese rich conditions the most stable structure is a MnN terminated surface. Whereas, from intermediate to nitrogen rich conditions, a MnN terminated surface with excess of nitrogen atoms is the most favorable. The stability of these surfaces can be traced to the formation of Mn–N bonds at the surface. The stable surfaces are Ferrimagnetic along the direction perpendicular to the surface, retaining a bulk-like behavior. However, there is a decrease in the Mn magnetic moments due to the presence of the surface. Density of states shows an asymmetric behavior, inherent of a Ferrimagnetic state. Finally, the surfaces are metallic with the main contributions around the Fermi level coming from the Mn-d orbitals. The knowledge about the atomic arrangements of the Mn4N surfaces may serve to explain and understand the formation of more complex and technologically applicable ferromagnetic/ferrimagnetic and antiferromagnetic/ferrimagnetic heterostructures.