⁵¹V NMR Study in the Paramagnetic State of LaVO_3

Abstract

The magnetic susceptibility (χ ) and the ⁵¹V Knight shift (K) measurements are performed on the perovskite LaVO₃ in the paramagnetic state. By analyzing the K-χ diagram, independent contributions of spin and orbital susceptibilities to the observed one are determined experimentally. The spin susceptibility was found to be suppressed from the Curie-Weiss law for S=1 spins well above the Néel temperature. It was also found that the hyperfine coupling constant for d spin is largely reduced from the usual core-polarization contribution. The analysis based on a local-moment model shows that this reduction may be caused by a large transferred hyperfine coupling between the neighboring V³⁺ ions rather than by covalency with O^2- ions. This accounts for all the NMR data rather quantitatively, though, the sign and the magnitude of the transferred hyperfine field are not compatible with any existing microscopic theories.