V-51 NMR-STUDY IN THE PARAMAGNETIC STATE OF LAVO3

The magnetic susceptibility (chi) and the V-51 Knight shift (K) measur ements are performed on the perovskite LaVO3 in the paramagnetic state . By analyzing the K-chi diagram, independent contributions of spin an d orbital susceptibilities to the observed one are determined experime ntally. The spin susceptibility was found to be suppressed from the Cu rie-Weiss law for S = 1 spins well above the Neel temperature. It was also found that the hyperfine coupling constant for d spin is largely reduced from the usual core-polarization contribution. The analysis ba sed on a local-moment model shows that this reduction may be caused by a large transferred hyperfine coupling between the neighboring V3+ io ns rather than by covalency with O2- ions. This accounts for all the N MR data rather quantitatively, though, the sign and the magnitude of t he transferred hyperfine field are not compatible with any existing mi croscopic theories.