Heavy Fermion metal Fe16N2 and its giant magnetic moment

A new model is proposed for the strong ferromagnetism associated with partially localized orbitals in the Fe16N2 metallic system which draws substantially from models of heavy fermion metals. The basic idea is that the spatially isolated Fe-N clusters generate non-uniform charge density and increase the d-d electron interaction significantly, leading to a highly spin polarized configuration for low lying 3d orbitals. Simulation based on LDA+U method is performed to illustrate the correlation between enhanced U and giant magnetic moment.