1303.1968 (Katalin Kamaras et al.)

Mott localization in the correlated superconductor Cs3C60 resulting from
the molecular Jahn-Teller effect    [PDF]

Katalin Kamaras, Gyongyi Klupp, Peter Matus, Alexey Y. Ganin, Alec McLennan, Matthew J. Rosseinsky, Yasuhiro Takabayashi, Martin T. McDonald, Kosmas Prassides

Cs3C60 is a correlated superconductor under pressure, but an insulator under ambient conditions. The mechanism causing this insulating behavior is the combination of Mott localization and the dynamic Jahn-Teller effect. We show evidence from infrared spectroscopy for the dynamic Jahn-Teller distortion. The continuous change with temperature of the splitting of infrared lines is typical Jahn-Teller behavior, reflecting the change in population of solid-state conformers. We conclude that the electronic and magnetic solid-state properties of the insulating state are controlled by molecular phenomena. We estimate the time scale of the dynamic Jahn-Teller effect to be above 10^(-11) s and the energy difference between the conformers less than 20 cm-1.

View original: http://arxiv.org/abs/1303.1968