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

Abstract

The ${\mathrm{V}}^{51}$ NMR frequency shift ($\frac{\Delta \nu }{\nu }$) in metallic ${\mathrm{V}}_2$ ${\mathrm{O}}_3$ has been measured in the temperature range of 175 to 575°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 ($\frac{\Delta \nu }{\nu }$)-versus-$\chi$ diagram. The $d$-band spin susceptibility ${\chi }_d$ is found to obey a Curie-Weiss law down to the transition temperature of about 160°K. A large temperature-independent orbital susceptibility is found to be ${\chi }_{\mathrm{VV}}\simeq 1.52\%$. From the temperature dependence of ${\chi }_d\mathrm{}\left(T\right)\mathrm{}$ and the corresponding frequency shift ${\left(\frac{\Delta \nu }{\nu }\right)}_d$, a negative hyperfine field of ${H_d}^{\mathrm{hf}}\simeq -140\mathrm{}$ 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°K. Contributions to the ${\mathrm{V}}^{51}$ NMR linewidth are discussed.