title: Specular scattering probability of acoustic phonons in atomically flat interfaces.
abstract: 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.
authors.affiliation: Department of Electrical Engineering and Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Wen
authors.forename: Chia-Lung
authors.initials: CL
authors.lastname: Hsieh
authors.forename: Kung-Hsuan
authors.initials: KH
authors.lastname: Lin
authors.forename: Hung-Pin
authors.initials: HP
authors.lastname: Chen
authors.forename: Shu-Cheng
authors.initials: SC
authors.lastname: Chin
authors.forename: Ching-Lien
authors.initials: CL
authors.lastname: Hsiao
authors.forename: Yuan-Ting
authors.initials: YT
authors.lastname: Lin
authors.forename: Chia-Seng
authors.initials: CS
authors.lastname: Chang
authors.forename: Yuan-Chih
authors.initials: YC
authors.lastname: Chang
authors.forename: Li-Wei
authors.initials: LW
authors.lastname: Tu
authors.forename: Chi-Kuang
authors.initials: CK
authors.lastname: Sun