Spin State of Co3+ in LaCo1−xRhxO3 Studied Using X-ray Absorption Spectroscopy

The electronic states in LaCo1−xRhxO3 have been investigated using X-ray absorption spectroscopy (XAS) to elucidate the Rh substitution effect on the Co spin state. The absorption spectra at the Co L2-edge and O K-edge reveal that the spin state of Co3+ shows spin-crossover behavior from a spin state with S = 1, which corresponds to the peculiar spin state of LaCoO3 in the intermediate-temperature region, to a high spin state with S = 2. Moreover, we clarify that weak ferromagnetism is realized in LaCo1−xRhxO3 (0.1 ≦ x ≦ 0.4), in which the ground state of Co3+ becomes an S = 1 spin state.