Ultrafast structural transition and electron-phonon/phonon–phonon coupling in antimony revealed by nonadiabatic molecular dynamics

• Published in: Journal of physics. Condensed matter 2024-11, Vol.37 (4), p.45401
• Main Authors: Niu, Meng, Qin, Shun-Yao, Wang, Bai-Qian, Chen, Nian-Ke, Li, Xian-Bin
• Format: Article
• Language: English
• Subjects: antimony; electron-phonon/phonon–phonon coupling; Peierls distortion; photoinduced structural transition; time-dependent density-functional theory molecular dynamics
• ISSN: 0953-8984; 1361-648X; 1361-648X
• DOI: 10.1088/1361-648X/ad8696

Real-time time-dependent density-functional theory molecular dynamics (rt-TDDFT-MD) reveals the nonadiabatic dynamics of the ultrafast photoinduced structural transition in a typical phase-change material antimony (Sb) with Peierls distortion (PD). As the excitation intensity increases from 3.54% to 5.00%, three distinct structural transition behaviors within 1 ps are observed: no PD flipping, nonvolatile-like PD flipping, and nonstop back-and-forward PD flipping. Analyses on electron-phonon and phonon-phonon couplings indicate that the excitation-activated coherent A phonon mode by electron-phonon coupling drives the structural transition within several hundred femtoseconds. Then, the energy of coherent motions are transformed into that of random thermal motions via phonon-phonon coupling, which prevents the A -mode-like coherent structure oscillations. The electron-phonon coupling and coherent motions will be enhanced with increasing the excitation intensity. Therefore, a moderate excitation intensity that can balance the coherent and decoherent thermal movements will result in a nonvolatile-like PD flipping. These findings illustrate important roles of nonadiabatic electron-phonon/phonon-phonon couplings in the ultrafast laser-induced structural transitions in materials with PD, offering insights for manipulating their structures and properties by light.