We have studied the electronic structure of multiferroic BiCoO3 using x-ray photoemission spectroscopy (XPS), x-ray absorption spectroscopy (XAS), and subsequent model calculations. The XAS results show that the Co3 + ion takes the high-spin d6 configuration which usually prefers G-type antiferromagnetic state. The XPS results and model Hartree-Fock calculations show that, in case of BiCoO3, small charge-transfer energy plays an essential role to enhance the Co-O-O-Co superexchange pathways. It is found that the combination of ferro-type orbital ordering of Co 3d t 2g and the Co-O-O-Co superexchange interaction gives rise to C-type antiferromagnetic state in BiCoO3. The present analysis suggests that, in addition to the Bi-O bonds responsible for the noncentrosymmetric deformation, the O-O bonds are important to stabilize the multiferroic phase of BiCoO3.
|ジャーナル||Physical Review B - Condensed Matter and Materials Physics|
|出版ステータス||Published - 2011 6 3|
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