Electronic and magnetic states in doped LaCoO 3

The electronic and magnetic states in doped perovskite cobaltites, $(\mathrm{L}\mathrm{a},\mathrm{S}\mathrm{r}){\mathrm{CoO}}_{3},$ are studied in the numerically exact diagonalization method on ${\mathrm{Co}}_{2}{\mathrm{O}}_{11}$ clusters. For realistic parameter values, it is shown that a high spin state and an intermediate spin state coexist in one-hole-doped clusters due to strong $p\ensuremath{-}d$ mixing. The magnetic states in the doped cobaltites obtained in the calculation explain various experimental results.