Sub-THz Raman response in BaTiO₃ and link with structural phase transition

Marc D. Fontana (1) , Ninel Kokanyan (1) , Thomas H Kauffmann (1)

1 LMOPS - Laboratoire Matériaux Optiques, Photonique et Systèmes

The THz and sub-THz polarized Raman response was measured in tetragonal and cubic phases of single domain BaTiO 3 crystal. A large peak was detected at very low wavenumber, within a scattering geometry in which all phonon lines are Raman inactive. It is lying below 700 GHz in the whole temperature range of the tetragonal phase, and is clearly distinct from the soft phonon band. This peak has relaxational behavior with a slowing down on approaching the phase transition from above and from below.

Mots clés: ferroelectrics; phase transitions; BaTiO 3; Raman spectroscopy; phonon; relaxation; order-disorder

Domaines: Physique [physics]; Matière Condensée [cond-mat]

Marc D. Fontana, Ninel Kokanyan, Thomas H Kauffmann. Sub-THz Raman response in BaTiO₃ and link with structural phase transition. Journal of Physics: Condensed Matter, 2020, 32 (28), pp.285403. ⟨10.1088/1361-648X/ab808e⟩. ⟨hal-02514778⟩