Spin-State Transition inRCoO3(R= La, Pr, and Nd): Single-Crystal59Co NMR Measurements

A thermally-induced spin-state transition in RC0O3 (R = La, Pr, and Nd) is investigated by single-crystal 59Co NMR measurements. In contrast to LaCoO3, PdCoC3 and NdCoC3 exhibit no clear transition but a crossover from a nonmagnetic state to a paramagnetic phase. Subtracting a rare-earth contribution to the 59Co Knight shift in PrCoC3 and NdCoC3, we obtain the hyperfine coupling constant between a 59Co nuclear spin and 3d spins in the paramagnetic state with the finite 3d spin susceptibility.