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"Origin of Orbital Ordering in KCuF3 and LaMnO3"

Relatore: E. Pavarini- Institüt für Festkörperperforschung and Institute for Advanced Simulation, Forschungszentrum Jülich Gmbh, Jülich, Germany

Aula Newton
16 Febbraio 2011 ore 16.00

In a seminal work Kugel and Khomskii showed that in strongly correlated systems with orbital degrees of freedom many-body effects can give rise to orbital order via a purely electronic super-exchange mechanism. Orbital-ordering phenomena are now believed to play a fundamental role in determining the electronic and magnetic properties of many strongly correlated oxides. The origin of orbital-order in real materials is, however, still controversial. The classical examples of orbitally-ordered systems are KCuF3 and LaMnO3. Using the LDA+DMFT approach we disentangle the effects of the different lattice distortions, electron localization, and many-body super-exchange and clarify the mechanism of orbital-order in these two paradigmatic compounds.