Melting and fragmentation of ultra-thin metal films due to ultrafast laser irradiation: a molecular-dynamics study

Using molecular-dynamics simulation, we study the response of thin metal films to a sudden energization, such as might be effected by ultrafast laser irradiation. For small energy densities, the film melts in a heterogeneous nucleation process, i.e. the melt front starts from the surfaces and runs into the material. Above a critical energy per atom, the film breaks. This occurs when the pressure in the molten film becomes strongly tensile, such that voids nucleate in the middle of the film. Upon coalescence of the voids the film fractures.