Graduate School of
Science and Engineering

In dielectrics, most of the energy is transferred by the motion of the atoms, or by the “phonons”, the quanta of the sound wave in matters. The phonons play important roles in ferroelectricity and in the thermal dynamics in dielectrics. In particular, some ferroelectric crystals allow the heat to become a “wave”, rather than to allow it only to diffuse as we experience usually. We use ultrafast laser sources to excite a “coherent wave of heat” in certain ferroelectric crystals. We also use an ultra-high (kHz) resolution stimulated Brillouin spectrometer to unveil the phonon linewidth in crystals and glass-forming materials at cryogenic temperatures. The high-resolution spontaneous Brillouin light scattering method is used, for example, to investigate the “fractal dynamics” in ferroelectric single crystals.