We investigated the pressure-dependent optical response of the low-dimensional Mott-Hubbard insulator TiOBr by transmittance and reflectance measurements in the infrared and visible frequency range. A suppression of the transmittance above a critical pressure and a concomitant increase of the reflectance are observed, suggesting a pressure-induced metallization of TiOBr. The metallic phase of TiOBr at high pressure is confirmed by the presence of additional excitations extending down to the far-infrared range. The pressure-induced metallization coincides with a structural phase transition, according to the results of x-ray powder diffraction experiments under pressure.
@article{arxiv.0710.4126,
title = {Pressure-induced metallization and structural phase transition of the Mott-Hubbard insulator TiOBr},
author = {C. A. Kuntscher and S. Frank and A. Pashkin and H. Hoffmann and A. Schönleber and S. van Smaalen and M. Hanfland and S. Glawion and M. Klemm and M. Sing and S. Horn and R. Claessen},
journal= {arXiv preprint arXiv:0710.4126},
year = {2012}
}