Crystalline Electric Field Effects in Ce<i>T</i>₂Al₁₀ (<i>T</i> = Ru, Os)

Abstract

We address crystalline electric field (CEF) effects in Ce T 2 Al 10 ( T = Ru, Os) showing novel phase transitions. Because of the absence of inversion symmetry with respect to the b coordinate in the m 2 m ( C 2 v ) site symmetry for Ce ions, there appears the unfamiliar odd-parity term H (o) in the CEF, as well as the ordinary even-parity term H (e) . The latter H (e) is used to determine the local 4 f electronic structure consistent with the experimental magnetic susceptibility. The former H (o) causes 4 f –5 d on-site mixing, whose effects on the Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction responsible for high transition temperatures and on the peak for the polarization along the b -axis in the optical conductivity are discussed.