Fast magnetization reversal of GdFeCo induced by femtosecond laser pulses

Pump-pulse induced magnetization reversal of amorphous ${\mathrm{Gd}}_{23.1}{\mathrm{Fe}}_{71.9}{\mathrm{Co}}_{5.0}$ showed a subpicosecond magnetization collapse followed by a slower reversal. The reversal dynamics is well described by the Bloch equation via a reversal time that does not depend on temperature, but strongly decreases with increasing pump fluence. A comparison to data obtained in external saturation field and in remanence opened the way to separate the contributions due to temperature induced effects within single domains from those related to field induced domain formation.