Phonon Softening and Dispersion in EuTiO3

Abstract

We measured phonon dispersion in single crystal EuTiO${}_3$ using inelastic x-ray scattering. A structural transition to an antiferrodistortive phase was found at a critical temperature $T_0$=287$\pm$1 K using powder and single-crystal x-ray diffraction. Clear softening of the zone boundary \emph{R}-point \textbf{q}=(0.5 0.5 0.5) acoustic phonon shows this to be a displacive transition. The mode energy plotted against reduced temperature could be seen to nearly overlap that of $\mathrm{SrTi}{\mathrm{O}}_3$, suggesting a universal scaling relation. Phonon dispersion was measured along $\Gamma$-$X$ (0 0 0)$\to$(0.5 0 0). Mode eigenvectors were obtained from a shell model consistent with the \textbf{q}-dependence of intensity and energy, which also showed that the dispersion is nominally the same as in $\mathrm{SrTi}{\mathrm{O}}_3$ at room temperature, but corrected for mass. The lowest energy optical mode, determined to be of Slater character, softens approximately linearly with temperature until the 70-100 K range where the softening stops, and at low temperature, the mode disperses linearly near the zone center.

5 pages, 4 figures

References in corpus (5)

• Magnetodielectric effect and optic soft mode behaviour in quantum paraelectric EuTiO3 ceramics
• Antiferrodistortive phase transition in EuTiO3
• First-principles prediction of oxygen octahedral rotations in perovskite-structure EuTiO3
• Magnetodielectric coupling and phonon properties of compressively strained EuTiO3 thin films deposited on LSAT
• Spin resonance in EuTiO3 probed by time-domain GHz ellipsometry

Cited by in corpus (8)

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• Lattice instabilities in bulk EuTiO3
• Structural and magnetic phase transitions in EuTi1-xNbxO3
• Ultrafast transient increase of oxygen octahedral rotations in a perovskite
• Introduction to High-Resolution Inelastic X-Ray Scattering
• Pressure-Temperature phase diagram of multiferroic EuTiO${}_3$
• Magnetic field driven novel phase transitions in EuTiO${}_3$
• Magnetic interactions and the puzzling absence of any Raman mode in EuTiO3