Berlin 2018 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 94: Correlated Electrons: Other Theoretical Topics

TT 94.1: Vortrag

Donnerstag, 15. März 2018, 15:00–15:15, H 3010

Charge disproportionation, mixed valence, and Janus effect in multi-orbital systems: A tale of two insulators — •Aldo Isidori, Maja Berovic, Laura Fanfarillo, Michele Fabrizio, and Massimo Capone — International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136 Trieste, Italy

We propose an interpretation for the Janus effect in multi-orbital electron systems, suggested by the duality between Jahn-Teller and Hund's metals at commensurate fillings. The effect emerges from the competition between two distinct insulating states, namely a Mott and a charge disproportionation insulator, favored either by the Coulomb interaction or the exchange coupling, respectively, and characterized by a different ionic valence. This competition results in an asymptotic mixed-valence metallic state, at arbitrarily large interaction strength, along the line where the two parent insulators are degenerate. In this state, charge fluctuations arise from the presence of hopping processes that connect the two degenerate insulators. Experimental evidence for the mixed-valence state and the charge disproportionation insulator-to-metal transition can be found in the chromium perovskite system.