title: Electronic-structure-driven magnetic ordering in a Kondo semiconductor CeOs2Al10.
abstract: We report the anisotropic changes in the electronic structure of a Kondo semiconductor CeOs(2)Al(10) across an anomalous antiferromagnetic ordering temperature (T(0)) of 29 K, using optical conductivity spectra. The spectra along the a and c axes indicate that an energy gap due to the hybridization between conduction bands and nearly local 4f states, namely the c-f hybridization gap, emerges from a higher temperature continuously across T(0). Along the b axis, on the other hand, another energy gap with a peak at 20 meV becomes visible at 39 K (>T(0)) and fully opens at T(0) because of a charge instability. This result implies that the appearance of the energy gap, as well as the change in the electronic structure along the b axis, induces the antiferromagnetic ordering below T(0).
authors.affiliation: UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan. kimura@ims.ac.jp
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Kimura
authors.forename: Takuya
authors.initials: T
authors.lastname: Iizuka
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Miyazaki
authors.forename: Akinori
authors.initials: A
authors.lastname: Irizawa
authors.forename: Yuji
authors.initials: Y
authors.lastname: Muro
authors.forename: Toshiro
authors.initials: T
authors.lastname: Takabatake