Analysis of - model for octupole ordering in NpO

Kubo, Katsunori; Hotta, Takashi

Physical Review B, 72(13), p.132411_1 - 132411_4, 2005/10

https://doi.org/10.1103/PhysRevB.72.132411

In order to examine the origin of octupole ordering in NpO, we propose a microscopic model constituted of neptunium and oxygen orbitals. To study multipole ordering, we derive effective multipole interactions from the - model by using the fourth-order perturbation theory in terms of - hopping integrals. Analyzing the effective model numerically, we find a tendency toward antiferro-octupole ordering.