Pressure-dependent electronic structures and orbital hybridization of Mn 3d states in multiferroic BiMnO 3: A combined x-ray absorption, x-ray emission, and resonant x-ray emission study
Journal
Physical Review B - Condensed Matter and Materials Physics
Journal Volume
86
Journal Issue
4
Date Issued
2012
Author(s)
Chen, J. M.
Haw, S. C.
Lee, J. M.
Chen, S. A.
Lu, K. T.
Chen, S. W.
Deng, M. J.
Liao, Y. F.
Lin, J. M.
Chen, B. H.
Hiraoka, N.
Ishii, H.
Tsuei, K. D.
Huang, E.
Abstract
We investigated both the dependence of electronic structures and spin states on pressure up to 25 GPa and the hybridization of Mn 3d states in BiMnO 3 by combining measurements of x-ray absorption, x-ray emission, and 1s3p-resonant x-ray emission spectroscopy (RXES). The Mn K-edge x-ray absorption spectra of BiMnO 3 show a great change for pressure ∼1 GPa, corresponding to the occurrence of a structural transition. The gradually diminished shoulder of the white line and subsequently increased intensity of the white line of Mn K-edge spectra on increasing the external pressure from 2 to ∼15 GPa are attributed to a diminished Jahn-Teller distortion of MnO 6 octahedra in BiMnO 3 with increasing pressure. For pressure >∼15 GPa, the intensity of the white line in Mn K-edge spectra of BiMnO 3 became progressively decreased. Preedge peaks in Mn K-edge spectra of BiMnO 3 at P = 25 GPa shifted to smaller energy ∼0.3 eV relative to P = 0.7 GPa. The spin magnetic moments deduced from the Kβ emission line show a significant decrease for pressures between 0 and 2 GPa, then a monotonic decrease for pressures between 2 and 7 GPa, and a slight decrease after 7 GPa. The 1s3p-RXES spectra obtained at the Mn-K preedge for BiMnO 3 reveal that the empty Mn 3d(eg0) states exhibit a delocalized character, suggested to originate from the hybridization of the unoccupied Mn 3d states with the Mn 4p orbitals. These findings provide insight into the evolution of electronic structures related to the structural transformation of multiferroic BiMnO 3 under pressure. © 2012 American Physical Society.
Type
journal article