Abstract
Quantum pathways inducing coherent lattice dynamics are studied in bismuth (Bi). A crystalline Bi film is excited by femtosecond midinfrared pulses and transient intensity changes on the (111) Bragg reflection are probed by hard x-ray pulses. A fast decrease and coherent oscillations of the diffracted intensity display up to 50% and 10% intensity change, respectively. The oscillation frequency of 2.6 THz is independent of pump intensity. Midinfrared excitation opens different quantum pathways for electron-hole generation, such as field-driven carrier tunneling at the points, which reduces the crystal symmetry and leads to optical phonon excitation at the point with the strongest electron-phonon coupling.
- Received 29 July 2022
- Revised 20 October 2022
- Accepted 9 May 2023
DOI:https://doi.org/10.1103/PhysRevB.107.L180303
©2023 American Physical Society