Phonon drag as a mechanism of delayed terahertz response of metals
Phys. Rev. B 114, 154301 – Published 2 September, 2026
DOI: https://doi.org/10.1103/qz25-c2fq
Abstract
We show that electron drag by nonequilibrium phonons describes the actual duration and spectrum of terahertz pulses generated during femtosecond laser irradiation of metals. In contrast to previous models, there is a picosecond delay in the drag force development due to the relatively slow lattice heating and finite phonon lifetime. We also predict that at high pump fluences a macroscopic deformation wave nonlinearly enhances the drag force and terahertz response. Our results establish the terahertz pulse wave form as a direct probe of ultrafast lattice dynamics in metals.
