Impulsive excitation of squeezed phonons in single crystal germanium by an x-ray laser
Abstract
In this Letter, we present the experimental observation of squeezed phonon generation in semiconductor germanium (Ge) induced by x-ray excitation. Prior x-ray pump, x-ray probe studies reported coherent longitudinal acoustic phonon generation in insulating oxides like strontium titanate and potassium tantalate. In contrast, such signals were not observed in semiconductors likely due to limited signal-to-noise ratio. Now, with an improved experimental setup, we observe a phonon response in single-crystal germanium. Utilizing x-ray split-delay optics with enhanced stability, we extract the phonon dispersion relation, which shows strong agreement with the calculated transverse acoustic phonon mode. Our results reveal that responses to x-ray excitations in semiconductors are of a similar nature to optical excitations. This suggests that the initial response to x-ray core–hole excitations rapidly diffuses to a non-local excitation, similar to what is observed with optical laser valence excitation on a femtosecond timescale.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (18)
Nan Wang
Haoyuan Li
Icahn Genomics Institute, Precision Immunology Institute, Department of Immunology and Immunotherapy, Department of Oncological Sciences, Tisch Cancer Institute, Biomedical Engineering and Imaging Institute, Friedman Brain Institute
Yanwen Sun
Linac Coherent Light Source, SLAC National Accelerator Laboratory
Dillon Hanlon
Department of Physics, Arizona State University 4 , Tempe, Arizona 85287,
Yijing Huang
Peihao Sun
Baochen She
Department of Physics, Stanford University 1 , Stanford, California 94305,
Chance Ornelas-Skarin
Department of Electrical Engineering, Stanford University 10 , Stanford, California 94305,
Samuel W. Teitelbaum
Department of Physics, Arizona State University 4 , Tempe, Arizona 85287,
Mark Sutton
Department of Physics, McGill University 11 , Montreal, Québec H3A 2T8,
Paul H. Fuoss
Linac Coherent Light Source, SLAC National Accelerator Laboratory 3 , Menlo Park, California 94025,
J. B. Hastings
Takahiro Sato
Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
Sanghoon Song
Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
Mariano Trigo
Stanford PULSE Institute, SLAC National Accelerator Laboratory 6 , Menlo Park, California 94025,
David A. Reis
Stanford PULSE Institute, SLAC National Accelerator Laboratory 6 , Menlo Park, California 94025,
Mike Dunne
Linac Coherent Light Source, SLAC National Accelerator Laboratory 3 , Menlo Park, California 94025,
Diling Zhu
Linac Coherent Light Source, SLAC National Accelerator Laboratory