Soft X-ray absorption spectroscopy study of multiferroic Bi-substituted Ba1−xBixTi0.9Fe0.1O3

The electronic structures of multiferroic oxides of Ba1−x Bi x Ti0.9Fe0.1O3 (0 ≤ x ≤ 0.12) have been investigated by employing photoemission spectroscopy and soft X-ray absorption spectroscopy (XAS). The measured Fe and Ti 2p XAS spectra show that Ti ions are in the Ti4+ states for all x and that Fe ions are Fe2+-Fe3+ mixed-valent for x > 0. The valence states of Fe ions are found to be nearly trivalent for x=0 and decrease with increasing x from being nearly trivalent (v(Fe) ~ 3) for x = 0 to v(Fe) ~ 2.6 for x = 0.12. The valence states of both Ti and Ba ions do not change for all x ≤ 0.12. Based on the obtained valence states of Fe ions, the electronic and the magnetic properties of Ba1−x Bi x Ti0.9Fe0.1O3 are explored.