Pressure and Temperature Dependence of Local Structure and Electronic Structure of Orthorhombic DyMnO3

The dependence on pressure and temperature of the local structure and electronic state for MnO6 octahedra in orthorhombic DyMnO3 is investigated with Raman scattering, lifetime-broadening-suppressed x-ray absorption spectra and x-ray emission spectra. With increasing pressure, all Raman-active modes of DyMnO3 persist and shift monotonically to greater wavenumbers, implying that no structural change occurs under an external pressure up to similar to 32 GPa. The spectral weight of the white line in Mn K-edge x-ray absorption spectra of DyMnO3 increased progressively, whereas the pre-edge feature gradually shifted to smaller energy upon increasing pressure. The Jahn-Teller distortion of MnO6 octahedra in DyMnO3 is progressively diminished with increasing pressure. The energy of the pre-edge line increased upon cooling from 300 to 10 K, in contrast with the pressure effect. A gradual breakdown of the high-spin state for MnO6 octahedra in DyMnO3 is observed. This work provides insight into structural modifications in highly distorted perovskite manganites under pressure and temperature.