Direct Measurement of Anharmonic Decay Channels of a Coherent Phonon

• Main Authors: Teitelbaum, Samuel W, Henighan, Tom, Huang, Yijing, Liu, Hanzhe, Jiang, Mason P, Zhu, Diling, Chollet, Matthieu, Sato, Takahiro, Murray, Éamonn D, Fahy, Stephen, O'Mahony, Shane, Bailey, Trevor P, Uher, Ctirad, Trigo, Mariano, Reis, David A
• Format: Journal Article
• Language: English
• Published: 21-10-2017
• Subjects: Physics - Materials Science
• DOI: 10.48550/arxiv.1710.02207

Phys. Rev. Lett. 121, 125901 (2018) We observe anharmonic decay of the photoexcited coherent A1g phonon in
bismuth to points in the Brillouin zone where conservation of momentum and
energy are satisfied for three-phonon scattering. The decay of a coherent
phonon can be understood as a parametric resonance process whereby the atomic
displacement periodically modulates the frequency of a broad continuum of
modes. This results in energy transfer through resonant squeezing of the target
modes. Using ultrafast diffuse x-ray scattering, we observe build up of
coherent oscillations in the target modes driven by this parametric resonance
over a wide range of the Brillouin zone. We compare the extracted anharmonic
coupling constant to first principles calculations for a representative decay
channel.