Anomalous Metal-Insulator Transition in Filled Skutterudite CeOs_4Sb_<12>

Anomalous metal-insulator transition observed in filled skutterudite CeOs4Sb12 is investigated by constructing the effective tight-binding model with the Coulomb repulsion between f electrons. By using the mean field approximation, magnetic susceptibilities are calculated and the phase diagram is obtained. When the band structure has a semimetallic character with small electron and hole pockets at г and H points, a spin density wave transition with an ordering vector Q = (1, 0, 0) occurs due to the nesting property of the Fermi surfaces. Magnetic field enhances this phase in accord with the experiments.Copyright(c)2006 The Physical Society of Japa