Local electronic structure and magnetic properties ofLaMn0.5Co0.5O3studied by x-ray absorption and magnetic circular dichroism spectroscopy

Abstract

We have studied the local electronic structure of $\mathrm{La}{\mathrm{Mn}}_{0.5}{\mathrm{Co}}_{0.5}{\mathrm{O}}_{3}$ using soft-x-ray absorption spectroscopy at the $\mathrm{Co}\text{\ensuremath{-}}{L}_{3,2}$ and $\mathrm{Mn}\text{\ensuremath{-}}{L}_{3,2}$ edges. We found a high-spin ${\mathrm{Co}}^{2+}\text{\ensuremath{-}}{\mathrm{Mn}}^{4+}$ valence state for samples with the optimal Curie temperature. We discovered that samples with lower Curie temperatures contain low-spin nonmagnetic ${\mathrm{Co}}^{3+}$ ions. Using soft-x-ray magnetic circular dichroism, we established that the ${\mathrm{Co}}^{2+}$ and ${\mathrm{Mn}}^{4+}$ ions are ferromagnetically aligned. We also revealed that the ${\mathrm{Co}}^{2+}$ ions have a large orbital moment: ${m}_{\mathrm{orb}}∕{m}_{\text{spin}}\ensuremath{\approx}0.47$. Together with model calculations, this suggests the presence of a large magnetocrystalline anisotropy in the material and predicts a nontrivial temperature dependence for the magnetic susceptibility.