Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 2: Correlated Electrons - Metal Insulator Transition

TT 2.6: Talk

Friday, March 4, 2005, 11:30–11:45, TU H2053

Charge order, orbital order, and electron localization in the Magnéli phase Ti₄O₇ — •V. Eyert, U. Schwingenschlögl, and U. Eckern — Institut für Physik, Universität Augsburg

The metal-insulator transition of the Magnéli phase Ti₄O₇ is studied by means of augmented spherical wave (ASW) electronic structure calculations as based on density functional theory and the local density approximation. The results show that the metal-insulator transition arises from a complex interplay of charge order, orbital order, and singlet formation of those Ti 3d states which mediate metal-metal bonding inside the four-atom chains characteristic of the material. Ti₄O₇ thus combines important aspects of Fe₃O₄ and VO₂ . While the charge ordering closely resembles that observed at the Verwey transition, the orbital order and singlet formation appear to be identical to the mechanisms driving the metal-insulator transition of vanadium dioxide.