Nuclear magnetic resonance of 51V(I=7/2) in lanthanide vanadates

Nuclear magnetic resonance of 51V(I=7/2) has been studied at temperatures down to 1.5K in single crystals of lanthanide vanadates LnVO4, where Ln3+ ranges from Pr3+,4f2 to Yb3+,4f13. The crystals are tetragonal, four molecules per unit cell, but all V5+ sites and all Ln3+ sites are magnetically equivalent. Measurements are made with applied fields parallel and perpendicular to the tetragonal axis. In this paper (I) values for the paramagnetic shifts are used to deduce the local fields at both the V5+ and Ln3+ sites. These fields are compared with the dipolar values, from which the magnitude of the transferred hyperfine interaction at the V5+ sites is deduced, together with estimates of the exchange interaction between the Ln3+ ions. The nuclear electric quadrupole interaction for 51V is discussed in paper II, and measurements in the antiferromagnetic phases of GdVO4and DyVO4 in paper III. (author)