Document Type
Article
Publication Date
11-5-2025
Publisher
AIP Publishing
Abstract
Excitation of coherent phonons has the potential to dramatically alter the electronic structure of Dirac and Weyl semimetals, enabling sub-picosecond control of their optical and electronic properties. The Dirac semimetal SrMnSb is a candidate for such control, with a coherent-phonon mode that is predicted to close and reopen a gap at the Dirac node. Here, through a series of ultrafast pump-probe experiments, we establish suitable samples and conditions for driving the coherent phonon to high amplitude and attempting to observe the gap’s closure. Films of SrMnSb grown by molecular-beam epitaxy are shown to have phononic properties matching those of bulk crystals. We find that the phonon can be strongly excited by pump pulses with wavelength near 1500 nm, which will excite a 30-nm film almost uniformly and will penetrate the arsenic capping layers that protect the films. We find that samples withstand pump pulses of fluence up to 20 mJ/cm , and we demonstrate the potential for sequences of pulses to amplify the oscillation while suppressing other phonon modes. Armed with our new knowledge of the conditions for exciting the desired coherent phonon, future experiments will be well prepared to measure its motion and to observe phononic control of the Dirac-point gap.
Recommended Citation
Rai, M., Subedi, S., Aguirre, H. E., Bechtel, H. A., Chapla, R., Garcia de Castro, J., Klug, D. D., Liu, J., Masten, M. G., Nguyen, T. H., Rehaag, T. J., Wang, Y., Mao, Z., Bell, G. R., Torchinsky, D. H., & Weber, C. P. (2025). Conditions of coherent-phonon excitation in SrMnSb2 films and crystals. Journal of Applied Physics, 138(17). https://doi.org/10.1063/5.0285134
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Comments
Includes dataset and supplemental file
© 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC) license (https://creativecommons.org/licenses/by-nc/4.0/). This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License .