J. Phys. IV France 7 (1997) C2-533-C2-534
Metal-Insulator Transition of VO2 . A XANES Investigation of the O K Edge of VO2O. Müller1, E. Goering1, J.P. Urbach1, T. Weber1, H. Paulin1, M. Klemm1, M.L. den Boer2 and S. Horn1
1 Institut für Physik, Lehrstuhl für Experimentalphysik II, Universität Augsburg, Memminger Strasse 6, 86159 Augsburg, Germany
2 Physics Dept., hunter College of CUNY, 695 Park Ave., New York NY 10021, U.S.A.
We have studied the metal-insulator (ME) transition in VO2 with angle resolved x-ray absorption spectroscopy. Above TMI the oxygen K near edge structure shows two resolved peaks, the intensities of which do not change if the polarization vector £ is related within the rutile (ab) piane, hut vary by a factor of two when E is rotated in the (ac) plane. Betow TMI we observe a third peak, which shows strong angular dependence: it vanishes for E ⊥ crut, and is largest for E || crut, confirming earlier suggestions that this peak is due to the so called d | band. We find analogous features in the M2 and T phases of Cr doped VO2 From comparisons of fliese spectra we conclude that shifls in the do band between the insulating and metallic phase are primarily due to the effect of correlations and the other shifts to the formation of rimers; tilting of the dtmers plays only a minor role.
© EDP Sciences 1997