Resistivity and Magnetic Order in Ti2O3

Abstract

Electrical resistivities of pure and vanadium-doped single crystals of Ti2O3 have been measured as a function of applied magnetic field strength and temperature. The anomalous high-temperature increase in electrical conductivity has been confirmed. It is argued that the symmetry of Ti2O3 leads naturally to a two-band model having bandwidths and an energy separation between band centers that are sensitive to the crystallographic axial ratio c/a. With this model, the change in conductivity with temperature can be adequately described on the basis of known variations in the c/a ratio with temperature. The vanadium-doped samples are good p-type conductors and exhibit a negative magnetoresistance at low temperatures. With a model of inelastic scattering at trace impurities carrying a localized magnetic moment, it is possible to describe the negative magnetoresistance of vanadium-doped samples provided the total, local (applied plus intrinsic) magnetic fields are within a few gauss of the applied field. It is concluded that the existence of antiferromagnetic order in Ti2O3 is in doubt and that the resistivity behavior can be readily interpreted without recourse to a magnetic-ordering mechanism.