Abstract
The dependence of the electronic structure and crystal structure of multiferroic YMnO 3 in an orthorhombic phase (o-YMnO3) on temperature up to 873K 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-YMnO 3 increases progressively, whereas the large equatorial bond distance (Mn-O2) l decreases with increasing temperature. The Mn-O-Mn angle of two adjacent MnO 6 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-YMnO 3 became suppressed, and the adjacent JTdistorted 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 MnO 6 octahedra in o-YMnO 3 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-Mn0 4p hybridization in o-YMnO3 with increasing temperature. The experimental and calculated, using code FDMNES, Mn K-edge spectra of o-YMnO 3 with various temperatures agree satisfactorily. This work provides insight into the structural stability of metastable o-YMnO 3 under high temperature. © 2013 The Physical Society of Japan.