Field-Induced Multipole States of Sm-Based Filled Skutterudites

Abstract

We discuss microscopic aspects of multipole properties of Sm-based filled skutterudite compounds under a magnetic field by analyzing a seven-orbital Anderson model with the use of a numerical renormalization group method. In order to determine the multipole state, we evaluate the susceptibility for the multipole operator defined in the form of one-body spin-charge density by the Wigner–Eckart theorem. We show our numerical results on entropy, specific heat, and multipole susceptibility of the seven-orbital Anderson model for the case of five f electrons at an impurity site under an applied magnetic field. Here we consider three directions of the magnetic field as [0, 0, 1], [1, 1, 0], and [1, 1, 1]. For all directions, dipoles and higher-rank multipoles with the same Γ 4u symmetry are induced, but depending on the direction of the magnetic field, characteristic multipoles are found to be additionally induced. For the [1, 1, 1] direction, we observe that Γ 2u octupole moment is induced, while for [0, 0, 1]...