Microscopic aspects of multipole properties of filled skutterudites

Hotta, Takashi

In order to develop a theory for multipole phenomena in -electron materials, we have proposed the construction of a microscopic model for -electron systems based on a - coupling scheme. By this approach, magnetism and superconductivity of filled skutterudites have been discussed from a microscopic viewpoint. In particular, we can also evaluate physical quantities related to multipoles by treating them as combined spin and orbital degrees of freedom. In this presentation, we will discuss three issues: (1) A concept of optimal multipole susceptibility to clarify the low-temperature properties of filled skutterudites. (2) An effective way to include the crystalline electric field potential of symmetry of filled skutterudites in the - coupling scheme. (3) Dynamical Jahn-Teller effects on multipole properties of filled skutterudites.