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TT: Fachverband Tiefe Temperaturen
TT 33: Postersession Correlated Electrons: Metal Insulator Transition, Spin Systems and Itinerant Magnets
TT 33.24: Poster
Mittwoch, 25. März 2009, 14:00–18:00, P1A
Spectral weight of Mott-Hubbard excitations in YVO3 studied by ellipsometry — •Julia Küppersbusch1, Christina Hilgers1, Agung Nugroho2, Thomas Palstra2, and Markus Grüninger1 — 1Universität zu Köln — 2Rijksuniversiteit Groningen
We investigate the optical conductivity of YVO3
between 0.75 and 5.5 eV from T=15 to 300 K
by means of ellipsometry.
Different groups reported contradictory data sets, none of them succeeded
in explaining the T dependence of the peak structure [1-3].
The compound YVO3 undergoes a series of
temperature-induced structural/electronic phase transitions.
The different phases show different spin/orbital ordering patterns, leading
to a pronounced anisotropy in the optical spectra.
The Mott-Hubbard gap of insulating YVO3 is located at 1.6 eV.
The strong increase of the optical conductivity above 4 eV is attributed to the
onset of charge-transfer (CT) excitations.
Below the CT transitions, the optical spectrum shows a three-peak structure with a complex T dependence.
This has been attributed to the different types of spin/orbital ordering, but a consistent description could
not be achieved.
Our data resolve the issue of the contradictory data sets.
We discuss the multiplet assignment of the different peaks and obtain an excellent understanding of the
T dependence of the optical conductivity.
[1] S. Miyasaka, Y. Okimoto, and Y. Tokura, J. Phys. Soc. Jpn. 71, 2086 (2002).
[2] A.A. Tsvetkov et al., Phys. Rev. B 69, 075110 (2004).
[3] J. Fujioka, S. Miyasaka, and Y. Tokura, PRB 77, 144402 (2008).