Laser-induced ultrafast structural transformations in thin Fe layer revealed by time-resolved X-ray diffraction

Abstract

The ultrafast structural response of a thin iron film to sub-ps pulsed laser-induced heating has been investigated using time-resolved X-ray diffraction in the partial melting regime. A tetragonal distortion of the bcc-phase emerges at ~6 ps. Its formation is delayed relative to the initial heating (1-2 ps) and partial melting (2-5 ps) of the material, and controlled by the stress release in the quasi-instantaneously pressurized film. The distortion persists for at least 60 ps indicating the formation of a metastable bct phase between the equilibrium bcc and fcc phases.

The revised manuscript features an upgraded discussion and conclusion parts, with particular emphasis on the role of stress-release mechanisms. The text has been substantially shortened and refined, with careful language improvements to ensure clarity and precision. Additionally, the manuscript has been formatted in accordance with PRL submission guidelines