J. Phys. IV France 7 (1997) C2-535-C2-536
Characterization of the Metallic and Insulating Phase of V2O3 and (V,Cr)2O3 by XANESJ.P. Urbach1, O. Müller1, E. Goering1, H. Paulin1, M. Klemm1, M.L. den Boer2 and S. Horn1
1 lnstitut 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 measured the O Is x-ray absorption of single crystals and epitaxial films of V2O3 in both metallic and insulating phases. The spectrum exhibits two peaks, the lower (higher) energy peak due to O 2p contributions to the t2g (eg) states. The spectra of all samples in the insulating state vary strongly with the angle between the surface normal and the polarization vector of the incident photons while the spectra of metallic samples are almost isotropic. On cooling t ie single crystal into the insulating phase, the higher energy peak increases in intensity, producing a spectrum similar to that found in the insulating Cr doped and pure V2O3 thin films, although the single crystal is then monoclinic while the films are not This implies that the change in the c/a ratio in the transition, not the lattice distortion, is primarily responsible for the change in electronic properties.
© EDP Sciences 1997