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Lecture Katalin Kamaras

Roster

WhenWhere
01 December 2011 FWN-Building 5113.0202, Nijenborgh 4, 9747 AG, Groningen
Speaker: Prof. Dr. Katalin Kamaras
Affiliation: Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Budapest
Title: Dynamic Jahn-Teller effect in expanded fullerides Cs3C60
Date: Thu Dec 1, 2011
Start: 10.00
Location: FWN-Building 5113.0201
Host: Petra Rudolf
Telephone: +31 50 363 4736

Abstract

The fulleride superconductors (A3C60, where A is an alkali metal) have been considered somewhat dull because the mechanism was supposed to be BCS. However, evidence is mounting for another model in these systems, similar to cuprates: a phase diagram where an antiferromagnetic Mott insulator is changing into a strongly correlated superconductor. Typical model systems are the so-called expanded fullerides where Mott localization happens because the distance between fulleride ions exceeds a critical value. Two cubic Cs3C60 polymorphs (A15 and fcc) are the newest members of this class, with transition temperatures around 35 K at a few kilobars. The normal state of these compounds is low-spin (S=1/2) indicating a spin-pairing mechanism for which the Jahn-Teller-effect was proposed. I will show that vibrational spectroscopy, exceptionally sensitive to molecular distortions, can unequivocally prove the dynamic Jahn-Teller effect in these materials, identifying them as „Mott-Jahn-Teller insulators”.

Last modified:22 October 2012 2.30 p.m.