Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 33: Postersession Correlated Electrons: Metal Insulator Transition, Spin Systems and Itinerant Magnets

TT 33.8: Poster

Mittwoch, 25. März 2009, 14:00–18:00, P1A

Electronic excitation spectra on undoped and electron doped TiOCl — •Roberto Kraus¹, Martin Knupfer¹, Michael Sing², and Ralph Claessen² — ¹IFW-Dresden, D-01069 Dresden, Deutschland — ²Experimentelle Physik 4, Universität Würzburg, D-97074 Würzburg

TiOCl as a low dimensional Mott insulator and a spin-Peierls compound has reached a lot of interest in the last years. TiOCl is a 3d¹ system with a half filled band. One way to reach a metal-insulator transition is a filling-controlled method by doping with electrons. In TiOCl exists a large van der Waals gap in the chlorine layers which can be intercalated easily, in our case with potassium. We present the electronic excitation spectrum of TiOCl measured by electron energy loss spectroscopy. For the undoped case we find no dispersion of the excitation above the Mott-gap. With increased doping this excitation splits into a lower and higher lying part. We also investigate the changes of the crystal structure with electron diffraction and find a complex behavior with different superstructures and an expanding lattice constant perpendicular to the Ti chains.