RESISTIVITY OF THE HIGH-TEMPERATURE METALLIC PHASE OF VO2

Measurements are reported of the electrical resistivity rho(T) along t he c axis of a single crystal Of VO2, from the metal-insulator transit ion at T = 333 K up to 840 K. The temperature dependence is very linea r, and a fit to Bloch-Gruneisen theory gives a residual resistivity rh o0 = 65 muOMEGA cm and a ratio rho(840 K)/rho0 = 8. With the help of a local-density-approximation band-structure calculation, we further pu rsue the conventional (Bloch-Boltzmann) interpretation by extracting t he electron-phonon coupling constant lambda = 1.1 and the mean free pa th l(800 K) = 3.3 angstrom. The short mean free path implies that the conventional interpretation is internally inconsistent. The most likel y explanation is that unknown internal damage (e.g., cracks) has alter ed the effective cross section of the sample, causing the measured res istivity to be overestimated by a factor greater-than-or-equal-to 3. A nother possibility is that, in common with the normal state of copper oxide superconductors, metallic VO2 may not be a conventional Fermi li quid.