Halfmetallic ferromagnetism in rare earth nitrides RENs (RE=Gd, Dy, and Ho): A first principles study

The structural, electronic, elastic and magnetic properties of three rare earth nitrides (RENs: RE=Gd, Dy, Ho) are investigated by first principles calculation using Vienna ab-initio simulation code (VASP). At ambient pressure all the three nitrides are stable in the ferromagnetic state (FM) with cubic NaCl(B1) structure. The calculated lattice parameters are in good agreement with experimental and other theoretical values. Electronic structure reveals that these materials are half metallic ferromagnets at normal pressure. A pressure induced structural phase transition from NaCl to wurtzite phase in GdN at 18.2 GPa and from NaCl to CsCl phase in DyN at 104 GPa and HoN at 138 GPa is also predicted. The half metallicity has been retained in GdN, DyN and HoN even after the phase transition but it vanishes at 73.18 GPa, 118 GPa and 141 GPa respectively. Ferromagnetism is quenched in all the three nitrides at a pressure of 252 GPa (GdN), 242 GPa (DyN) and 236.7 GPa (HoN).