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|Date and time:||29th Jan. (Thu.) 16:15〜|
|Place:||SPring-8, "HOUKOUKAN" seminar room|
|Title:||Theory of intermetallic charge transfer and insulator-metal transition in BiNiO3|
|講演者:||妹尾 仁嗣 氏 （理研）|
|Speaker:||Dr. Hitoshi Seo (RIKEN)|
Perovskite oxide BiNiO3 has been attracting interests owing to its huge negative thermal expansion under pressure .
At low pressure, the system is a charge ordered insulator where Bi3+ and Bi5+ are arranged, while at higher pressure by raising the temperature a phase transition to a metallic state via charge transfer from Ni to Bi is observed; the volume drastically decrease there, namely, the thermal expansion coefficient becomes negative.
In this study, we construct an effective model describing this peculiar phase transition in BiNiO3, to elucidate its microscopic origin and discuss the pressure-temperature phase diagram of this system .
 M. Azuma et al, Nature 2, 347 (2011).
 M. Naka, H. Seo, and Y. Motome, unpublished (JPS 70th Annual meeting 24aBF).