Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 34: Correlated Electrons: Metal-Insulator Transition 2
TT 34.5: Vortrag
Donnerstag, 28. Februar 2008, 15:00–15:15, H 2053
Pressure-induced phase transitions in the oxyhalides TiOX — •Christine Kuntscher1, Simone Frank1, Alexej Pashkin1, Helge Hoffmann1, Matthias Klemm1, Siegfried Horn1, Andreas Schönleber2, Sander van Smaalen2, Sebastian Glawion3, Michael Sing3, and Ralph Claessen3 — 1Experimentalphysik 2, Universität Augsburg, D-86135 Augsburg, Germany — 2Laboratory of Crystallography, Universität Bayreuth, 95440 Bayreuth, Germany — 3Experimentelle Physik 4, Universität Würzburg, D-97074 Würzburg, Germany
The titanium oxyhalides TiOX (X=Cl,Br) are spin-Peierls compounds with exotic properties. With the electronic configuration 3d1 they are Mott-Hubbard insulators with a charge gap of ≈2 eV. They were discussed to exhibit a resonating valence bond state and high-temperature superconductivity upon doping. However, up to now a metallization upon doping was not successful. Our recent pressure-dependent infrared spectroscopic investigations on TiOCl suggest that the application of external pressure is an alternative way to induce an insulator-to-metal transition in TiOX [1]. We have extended our spectroscopic investigations on TiOX to the far-infrared range, in order to verify the pressure-induced metallization. X-ray powder diffraction measurements under pressure show that the insulator-to-metal transition coincides with a structural phase transition.
We acknowledge the ANKA Angströmquelle Karlsruhe and the ESRF for the provision of beamtime and the DFG for financial support.
[1] C. A. Kuntscher et al., Phys. Rev. B 74, 184402 (2006).