First-principles study of structural, electronic, magnetic, optical, and magneto-optical properties of NpN

Abstract

We study the structural, electronic, magnetic, optical, and magneto-optical properties of NpN in detail using the fully relativistic full-potential calculations based on the density functional theory within the local spin density approximation. We successfully reproduce the positive sign of the electric field gradient (EFG) at Np nuclei. The positive EFG is in striking contrast to the negative EFG in a Np3+ free ion, indicating the importance of the interplay between spin-orbit coupling and covalent bonding in NpN. Also, the calculated band structure shows large splittings induced by spin polarization and spin-orbit coupling, suggesting that both effects are indispensable for understanding the electronic properties of this material. This results in a large Kerr rotation angle of about 2°, which is comparable to those of uranium calcogenides. ©2008 The Physical Society of Japan.