Spin states of Mn and Co inLaMn0.5Co0.5O3

Abstract

High-temperature susceptibility measurements have indicated that the spin states of Mn and Co are different in the two different phases of the ferromagnetic oxide ${\mathrm{LaMn}}_{0.5}{\mathrm{Co}}_{0.5}{\mathrm{O}}_{3}.$ Mn and Co ions are present in their trivalent state as high-spin ${\mathrm{Mn}}^{3+}$ and low-spin ${\mathrm{Co}}^{3+}$ in the high-${T}_{c}$ ${(T}_{c}\ensuremath{\approx}225 \mathrm{K})$ phase of the compound whereas in the low-${T}_{c}$ ${(T}_{c}\ensuremath{\approx}150 \mathrm{}\mathrm{K})$ phase, they are present as ${\mathrm{Mn}}^{4+}$ and ${\mathrm{Co}}^{2+}.$ Evidently, the ferromagnetic superexchange interactions are of different origins in the two different phases of ${\mathrm{LaMn}}_{0.5}{\mathrm{Co}}_{0.5}{\mathrm{O}}_{3}.$