Second sound in SrTiO3.
We study collective phonon excitations in SrTiO3 by low-frequency light scattering. We employ extended thermodynamics for phonon gas to construct a theoretical spectral function that is applicable regardless of local thermal equilibrium. Our analysis reveals the temperature dependence of tauN, the relaxation time for the momentum-conserving phonon collisions (normal processes), in SrTiO3. These results indicate that the previously reported anomalous soundlike spectrum originates from second sound, which is a wavelike propagation of heat.
Koreeda
Akitoshi
A
Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
Takano
Ryuta
R
Saikan
Seishiro
S