• Yu-Chieh Wen, Chia-Lung Hsieh, Kung-Hsuan Lin, Hung-Pin Chen, Shu-Cheng Chin, Ching-Lien Hsiao, Yuan-Ting Lin, Chia-Seng Chang, Yuan-Chih Chang, Li-Wei Tu, and Chi-Kuang Sun, Physical Review Letters 103(26), 264301 (2009) Website
    Specular scattering probability of acoustic phonons in atomically flat interfaces
We report a direct determination of the specular scattering probability of acoustic phonons at a crystal boundary by observing the escape of incident coherent phonons from the coherent state during reflection. In the sub-THz frequency range where the phonon wavelength is much longer than the lattice constant, the acoustic phonon-interface interaction is found to agree well with the macroscopic theory on wave scattering from rough surfaces. This examination thus quantitatively verifies the dominant role of atomic-scale corrugations in the Kapitza anomaly observed at 1–10 K and further opens a new path to nondestructively estimate subnanoscale roughness of buried interfaces.