Anisotropic acoustic deformation potential characterization via coherent acoustic phonons in black phosphorus for dynamical strain sensor
Phys. Rev. B 114, 105137 – Published 24 August, 2026
DOI: https://doi.org/10.1103/s24b-d85y
Abstract
Ultrafast pump-probe spectroscopy was utilized to investigate coherent acoustic phonon (CAP) generation in bulk black phosphorus on substrate, focusing on its dependence on probe wavelength, pump wavelength, and polarization. By systematically varying the pump wavelength from 400 to 800 nm, we quantitatively extracted the acoustic deformation potential (ADP) values that characterize carrier-acoustic phonon interactions in anisotropic semiconductors. The analysis reveals that both the ADP mechanism and thermoelastic stress contribute comparably to CAP generation, with their relative weights strongly dependent on excitation conditions. Pronounced anisotropy was observed when tuning the pump polarization between the armchair and zigzag (ZZ) crystallographic directions, yielding ADP values of 6.96 and 2.70 eV, respectively. Complementary density functional theory calculations and a two-valley coupling model indicate that the reduced effective ADP for pump polarization along the ZZ direction originates from intervalley carrier scattering and multivalley conduction band contributions. In this study, we establish CAP spectroscopy as a powerful, polarization-resolved probe of electron-phonon coupling and provide a general framework for quantifying deformation potentials in anisotropic, multivalley materials.
