Contributions to theV51Nuclear Magnetic Resonance Frequency Shift and Susceptibility in Vanadium Sesquioxide

Abstract

The ${\mathrm{V}}^{51}$ NMR frequency shift ($\frac{\ensuremath{\Delta}\ensuremath{\nu}}{\ensuremath{\nu}}$) in metallic ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ has been measured in the temperature range of 175 to 575\ifmmode^\circ\else\textdegree\fi{}K the frequency shift at these two temperatures being -0.61% and +0.1%, respectively. Various contributions to the frequency shift and magnetic susceptibility are determined by constructing a ($\frac{\ensuremath{\Delta}\ensuremath{\nu}}{\ensuremath{\nu}}$)-versus-$\ensuremath{\chi}$ diagram. The $d$-band spin susceptibility ${\ensuremath{\chi}}_{d}$ is found to obey a Curie-Weiss law down to the transition temperature of about 160\ifmmode^\circ\else\textdegree\fi{}K. A large temperature-independent orbital susceptibility is found to be ${\ensuremath{\chi}}_{\mathrm{VV}}\ensuremath{\simeq}1.52%$. From the temperature dependence of ${\ensuremath{\chi}}_{d}(T)$ and the corresponding frequency shift ${(\frac{\ensuremath{\Delta}\ensuremath{\nu}}{\ensuremath{\nu}})}_{d}$, a negative hyperfine field of ${{H}_{d}}^{\mathrm{hf}}\ensuremath{\simeq}\ensuremath{-}140$ kOe/Bohr magneton, resulting from core polarization, a temperature-dependent orbital hyperfine field, and a dipolar hyperfine field, is found. With decreasing temperature the ${\mathrm{V}}^{51}$ NMR signal abruptly disappears at the transition temperature, suggesting that ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ undergoes antiferromagnetic ordering for temperatures less than 160\ifmmode^\circ\else\textdegree\fi{}K. Contributions to the ${\mathrm{V}}^{51}$ NMR linewidth are discussed.