Additional carrier-mediated ferromagnetism in GdN

The mechanism behind ferromagnetic exchange interaction in GdN is not well understood. It has been argued that it can be due to fourth-order cross process of d-f mixing and d-f exchange. An alternative explanation suggests an antiferromagnetic interaction between Gd d and N p induced moments on the rock salt structure which aligns the nearest-neighbor Gd f moments ferromagnetically through the d-f exchange. In this paper, we present results of Curie temperature in GdN as a function of carrier density calculated within our multiband modified RKKY-like exchange interaction. It includes realistic bandstructure of the 5d conduction band as an input for single particle energies. We analyze the possibility of carrier-mediated ferromagnetism in GdN and also demonstrate a simple phenomenological model which justifies the role of charge carriers.