Observation of coherent high-wavevector acoustic vibrations in a bulk material using time-resolved X-ray diffraction
ORAL
Abstract
We report on the observation of high-wavevector acoustic phonons in bulk InP that originate from folded phonons in a GaInAs/AlInAs superlattice. Synchrotron time-resolved X-ray diffraction is used to probe the evolution of the laser-generated acoustic phonons. Due to the short wavelength, X-ray diffraction gives access high-wavevector components of the acoustic wave-packet in a bulk material. Experiments show a bulk excitation at a wavevector $q=2 \pi/D$, where $D$ is the superlattice period, which propagates into the substrate at the speed of sound. These results are supported by time-resolved dynamical diffraction calculations in which the strain is included as a perturbation from the perfect crystal.
*This work was conducted at the sector 7 insertion device beamline at the APS and was supported in part by the U.S. DoE and from the NSF FOCUS physics frontier center.
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