We have investigated a metal-insulator transition in a (formula presented) -electron system (formula presented) (formula presented) and Y) by means of optical spectroscopy. The electronic structure is reconstructed over an energy range of several electron volt upon the transition. The insulating (formula presented) compound shows an optical gap of ca. 0.1 eV at 10 K and the temperature dependence of optical conductivity is rather weak. On the other hand, metallic (formula presented) exhibits a tiny Drude-peak and strong mid-infrared absorption at 10 K and the conductivity strongly depends on temperature. These observations demonstrate the importance of correlation effect also in (formula presented) -electron system with a wider bandwidth than (formula presented) -electron system.
|ジャーナル||Physical Review B - Condensed Matter and Materials Physics|
|出版ステータス||Published - 2002 1 1|
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