Koreeda Akitoshi, Takano Ryuta, Saikan Seishiro
Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
Phys Rev Lett. 2007 Dec 31;99(26):265502. doi: 10.1103/PhysRevLett.99.265502. Epub 2007 Dec 28.
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.
我们通过低频光散射研究了SrTiO₃中的集体声子激发。我们采用声子气体的扩展热力学来构建一个理论光谱函数，该函数适用于任何局部热平衡情况。我们的分析揭示了SrTiO₃中动量守恒声子碰撞（正常过程）的弛豫时间tauN的温度依赖性。这些结果表明，先前报道的异常类声光谱源自第二声，即热的波状传播。
