Ultra-fast disordering by fs-lasers: Lattice superheating prior to the entropy catastrophe

作者：Gamaly Eugene G^*

来源：Applied Physics A-Materials Science & Processing, 2010, 101(1): 205-208.

DOI：10.1007/s00339-010-5779-9

Point defects and lattice heating are two major sources for the catastrophic disordering of a crystal in equilibrium. I demonstrate that the thermal point defects formation time in a femtosecond laser (fs-laser)-excited solid is the longest of all relaxation times, while the ultra-fast contribution to the entropy changes from electrons is minor in comparison to the catastrophe value. Thus non-thermal disordering solely by electron excitation prior to the energy transfer to the lattice is proved to be thermodynamically impossible. The swiftly excited solid can be disordered only if a lattice is superheated over the critical temperature defined by the entropy catastrophe. The presented analysis of experiments on fs excitation of different solids is consistent with theory.

• 出版日期2010-10