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.
Wen
Yu-Chieh
YC
Department of Electrical Engineering and Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan.
Hsieh
Chia-Lung
CL
Lin
Kung-Hsuan
KH
Chen
Hung-Pin
HP
Chin
Shu-Cheng
SC
Hsiao
Ching-Lien
CL
Lin
Yuan-Ting
YT
Chang
Chia-Seng
CS
Chang
Yuan-Chih
YC
Tu
Li-Wei
LW
Sun
Chi-Kuang
CK