抄録
A new feature of Kondo effect due to an orbitally degenerate impurity is presented for a crystal-field singlet–triplet case in the f2 configuration. There are two stable states at low temperatures: one is a Fermi-liquid dominated by the f2 singlet; the other is a non-Fermi liquid stabilized by a quadrupolar type of exchange interaction between the f2 triplet and conduction electrons. The numerical renormalization group analysis shows that the competition of both states strongly enhances a coupling of conduction electrons with a scalar type of hexadecapolar moment of the impurity state, indicating that the charge degrees of freedom is relevant for the multiorbital case. This result supports the superiority of high-rank multipoles in f-electron systems such as the Pr-based filled skutterudite compounds.
