Possible multipole state of SmRuP probed by SR

Ito, Takashi   ; Higemoto, Wataru  ; Oishi, Kazuki*; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; Sato, Hideyuki*

The filled skutterudite compound SmRuP exhibits a metal-insulator (MI) transition at 16.5 K. An entropy release below suggests that the crystalline-electric-field ground state is a quartet with various multipole degrees of freedom. A possibility of magnetic octupole ordering has been intensively discussed to explain the time-reversal-symmetry breaking, anomalous elastic properties, and a complex field-temperature phase diagram. We will report SR measurements on single crystalline samples of SmRuP to investigate the nature of the multipoles in the ordered state. A remarkable longitudinal relaxation was observed in the ordered state, the magnitude of which was reduced below 3 K. We will discuss possible low-energy excitations of magnetic multipoles in the ordered state and their influence on the local magnetic probe on the basis of symmetry of the multipoles.