DFT study of magneto-volume effects in iron and cobalt nitrides

Largely investigated, both theoretically and experimentally, the iron-nitrogen system (Fe-N) shows large magneto-volume effects, where N element plays an important role. On the other side, the cobalt-nitrogen (Co-N) system magnetic properties are less known. We present here a first principles comparative study, within density functional theory framework of these two systems in order to get further insights into the role of nitrogen within these insertion alloys. The properties of the cobalt nitride are firstly discussed with respect to Fe-N ones, and then the two systems are treated within Slater-Pauling-Friedel model whose limitations are shown.