de Haas–van Alphen Effect in EuRu₄Sb₁₂

Abstract

We report the first successful observation of the de Haas-van Alphen (dHvA) effect in Eubased filled skutterudite EuRu4Sb12 which shows a ferromagnetic transition at TC = 3.3 K. The dHvA frequencies and those angular dependences are highly different from those for the trivalent compounds such as LaRu4Sb12 and PrRu4Sb12. This fact is consistent with the results of magnetic susceptibility and the X-ray absorption near edge spectroscopy measurements which have revealed a nearly divalent Eu electronic configuration. The cyclotron effective masses have been estimated ranging from 1.6m0 to 2.6m0.KEYWORDS: EuRu4Sb12, de Haas-van Alphen effect IntroductionThe filled-skutterudite compounds with chemical formula of RT r 4 X 12 (R= rare earth, T r= Fe, Ru, or Os, and X=pnictogen) have attracted much attention because almost all the strongly correlated electron phenomena, i.e., heavy fermion (HF) state, metal-insulator (M-I) transition, anisotropic superconductivity etc., have been realized in a same crystal structure.1-3 RT r 4 X 12 crystallizes in the bcc LaFe 4 P 12 -type structure (space group Im3) in which R atoms are located in an oversized atomic cage formed by the T r 4 X 12 . Relatively large distance between R-and X-ions leads to the small c − f hybridization strength between each pair of R-and Xions, however, the large coordination number (12 X-ions surrounding a R-ion) gives rise to the resultant effective large c − f hybridization, even in the compounds containing the R-atoms with more than one 4f -electron. Such a unique crystallographic structure is believed to be an origin of the strongly correlated electron phenomena observed in the filled-skutterudite compounds. Among the family of filled-skutterudite compounds, rare earth filled-skutterudite antimonides RT 4 Sb 12 have been the subjects of intense studies because of novel physical properties such as non-Fermi liquid behavior in CeRu 4 Sb 12 , 4 Kondo insulating behavior in CeOs 4 Sb 12 ,

Nuclear Quadrupole Resonance Measurement of the Ferromagnetic Filled-Skutterudite Compound EuRu4Sb12

“…6) The samples were crushed into powder for the NQR experiments. The NQR measurements were carried out using a phase-coherent pulse spectrometer.…”