Anomalous electric and magnetic properties ofV2O3in the metallic state

Abstract

Assuming the Hubbard model for the tightly bound $a_{1g}$ electrons of the two pairs of V atoms within the unit cell of metallic ${\mathrm{V}}_2$ ${\mathrm{O}}_3$, we have studied the correlated ground and excited molecular states. Using the exact wave functions of the singlet ground state and of the first excited triplet state, we evaluate the molecular magnetic susceptibility ${\chi }_0\left(\omega \right)$. The susceptibility of the conduction ($e_g$) electrons $\chi (\mathbf{q},\omega )$ is obtained in terms of ${\chi }_0$ and the conduction-electron polarizability. The conduction-electron mass renormalization $\frac{m^{*}}{m_b}$ is due to the virtual magnetic excitations of the $a_{1g}$ electrons, introducing antiferromagnetic correlations between the V pairs. The resistivity $\rho =A{T}^2$ is caused by virtual exchange of these excitations. Both quantities are obtained from $\chi (\mathbf{q},\omega )$. The results are discussed in terms of the pertinent parameters in $\chi$, such as the intra-atomic exchange interaction between the $a_{1g}$ and $e_g$ electrons, and are compared with the experimental results. Because the antiferromagnetic spin-fluctuation model does not account for the susceptibility enhancement at $q=0\mathrm{}$ and because $A$ is not sufficiently large we use Landau's Fermi-liquid theory to arrive at a consistent quasiparticle description of metallic ${\mathrm{V}}_2$ ${\mathrm{O}}_3$. The Landau scattering parameters $A_1$ are obtained by applying the potential-scattering model for the quasiparticle interaction due to the molecular magnetic excitations. It is found that the experimental values for the specific heat, the static susceptibility, and the electrical resistivity can be explained in a consistent manner.