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TT: Tiefe Temperaturen

TT 24: Postersitzung III: Korrelierte Elektronen, ”Orbital Physics”

TT 24.55: Poster

Wednesday, March 10, 2004, 14:30–19:00, Poster A

Orbital ordering in manganites on the band approach. — •Dmitry Efremov¹ and Daniel Khomskii² — ¹Technische Universität Dresden, Institut für Theoretische Physik, 01062 Dresden — ²Universität zu Köln, 50937 Köln

We consider the orbital ordering in LaMnO₃ and similar systems, proceeding from the band picture. We show that for the realistic magnetic structure of A-type there exists a complete nesting between two e_g-bands. As a result there occurs an instability towards Q=(π,π) an excitonic insulator like state – an electron-hole pairing with the wave vector, which opens a gap in the spectrum and makes the system insulating. In the resulting state there appear an orbital ordering – orbital density wave (ODW), the type of which coincides with these existing in LaMnO₃.