Role of microscopic coherent force and hot-carrier cooling in photoinduced phase transition for chalcogenide phase-change materials

The nonequilibrium ultrafast carrier dynamics of the photoinduced phase transition in chalcogenide phase-change material (rocksalt Ge-Sb-Te) has been investigated via real-time time-dependent density-functional theory, reproducing experimental observations of subpicosecond timescales and electronic diffraction. We develop a picture of the photocarrier distribution in momentum and real space dependent on the laser external field, revealing that thermal and coherent phonons contend to modulate the crystalline order. Localized coherent Peierls suppression intensifies with electronic excitation, and ultrafast dissipation of antibonding electrons near the Fermi surface incubates Lindemann particles. Full-domain hot-carrier excitation upon intense photon scattering cools and participates in the self-amplified growth of molten particles, followed by a sustained nonradiative recombination of photoelectron and photogenerated hole pairs. These findings present a comprehensive and definitive energy landscape for the nonequilibrium phase engineering in chalcogenide phase-change materials.