Dislocation-mediated vortex-lattice melting in thin films ofa-Nb3Ge

Resistivity and I-V measurements have been performed on thin amorphous ${\mathrm{Nb}}_3$Ge films in perpendicular fields. In the vicinity of the mean-field-transition line, pure flux-flow behavior occurs due to melting of the vortex lattice. The dependence of the melting field on temperature and thickness is well described by the melting theory for a two-dimensional lattice. In the narrow crossover regime between melting and weak pinning, dislocation-mediated flux creep occurs prior to melting.