Electronic structure and crystal structure of multiferroic o-YMnO3 at high temperature
Journal
Journal of the Physical Society of Japan
Journal Volume
82
Journal Issue
12
Date Issued
2013
Author(s)
Haw, S. C.
Lee, J. M.
Chen, S. A.
Lu, K. T.
Hiraoka, N.
Ishii, H.
Tsuei, K. D.
Lee, C. H.
Chen, J. M.
Abstract
The dependence of the electronic structure and crystal structure of multiferroic YMnO3 in an orthorhombic phase (o-YMnO3) on temperature up to 873 K was investigated on combining the measurements of synchrotron x-ray powder diffraction (SXRD) and high-resolution x-ray absorption spectra measured in the partial fluorescence yield. Based on SXRD refinement, the small equatorial bond distance (Mn–O2)s of o-YMnO3 increases progressively, whereas the large equatorial bond distance (Mn–O2)l decreases with increasing temperature. The Mn–O–Mn angle of two adjacent MnO6 octahedra increases monotonically with increasing temperature. Based on these SXRD results, the local Jahn–Teller (JT) distortion of Mn sites within MnO6 octahedra of o-YMnO3 became suppressed, and the adjacent JT-distorted MnO6 octahedra became progressively symmetric with increasing temperature. The white-line profile of Mn \(K\)-edge spectra becomes more symmetric, originating from the suppression of the Jahn–Teller distortion of MnO6 octahedra in o-YMnO3 at higher temperature. The pre-edge peak of Mn \(K\)-edge absorption spectra of o-YMnO3 increased in intensity and shifted to smaller energy at high temperatures, indicating a symmetric local structure of MnO6 octahedra and an increased contribution of the off-site Mn \(3d\)–Mn\('\) \(4p\) hybridization in o-YMnO3 with increasing temperature. The experimental and calculated, using code FDMNES, Mn \(K\)-edge spectra of o-YMnO3 with various temperatures agree satisfactorily. This work provides insight into the structural stability of metastable o-YMnO3 under high temperature.
Type
journal article