Soft X-ray Magnetic Circular Dichroism in La_1-xSr_xMnO₃ and SrFe_1-xCo_xO₃

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We have studied the magnetic and electronic states of La_1-xSr_xMnO₃ and SrFe_1-xCo_xO₃ by soft x-ray magnetic circular dichroism (SXMCD) measurements at the Mn, Fe and Co L_{2, 3}, and the O K core-absorption edges. An application of the SXMCD orbital sum rule to the L_2,3 SXMCD data clearly shows that the average orbital magneic moment (m_orb) of the nominal Mn³⁺ and Mn⁴⁺ ions is finite but small in La_1-xSr_xMnO₃, and that m_orb of the nominal Fe⁴⁺ ion is almost zero whereas m_orb of the nominal Co⁴⁺ ion is large in SrFe_1-xCo_xO₃. An SXMCD was also observed at the O K edge, showing spin polarization of the O 2p state. These results provide evidence that the nominal Mn³⁺, Mn⁴⁺, Fe⁴⁺, and Co⁴⁺ ions are dominantly in the highly charge-transferred d⁵L, d⁴L, d⁵L and d⁶L configurations, respectively, with L denoting the oxygen 2p hole.