Magnetic Excitations in Heavy Electron State of Filled Skutterudite Pr_<i>x</i>La_1-<i>x</i>Fe₄P₁₂ (<i>x</i> = 1.00 and 0.85)

Abstract

PrFe 4 P 12 exhibits clear heavy electron behaviors as well as the phase transition to an antiferro-type ordering of 4 f electron state. In this paper, we report on inelastic neutron scattering results for powdered samples of Pr x La 1- x Fe 4 P 12 ( x = 1.00 and 0.85). A clear quasielastic magnetic response is observed, and no distinct signal is seen for crystal-field (CF) excitations in the heavy electron state. A model with strong hybridization between conduction electrons and Pr 3+ 4 f 2 electrons [J. Otsuki et al. : J. Phys. Soc. Jpn. 74 (2005) 200 and 2082] is consistent with the observed magnetic response. This result shows that the heavy electron behavior of Pr x La 1- x Fe 4 P 12 ( x = 1.00 and 0.85) originates from the Kondo effect associated with low-lying singlet–triplet CF states.