37th CEMS Colloquium


Prof. Zenji Hiroi (The University of Tokyo)


17:30 - 18:30, March23, 2016 (Wednesday)


Okochi-Hall, RIKEN


Revisit the metal–insulator transition of VO2


The metal–insulator transition (MIT) of VO2 is one of the most dramatic phenomena so far found in transition metal compounds and is potentially important for application devices such as sensors and smart windows. The mechanism of the MIT has been studied a lot for decades, but still remains controversial: there is a history of tug-of-war between two sects emphasizing band effects and electron correlations. I happened to have a chance to revisit this long- standing issue from a different viewpoint that is a spinodal decomposition in the TiO2-VO2 system. In this talk I will try to convince the audience that the MIT of VO2 is nothing to do with electron correlations but is caused by a structural transition to a molecular orbital crystal (MOC). The idea of the MOC is quite general and may be helpful in understanding many electronic transitions in various classes of transition metal compounds.