Vortex Dynamics in Two-Dimensional Amorphous Mo77Ge23Films

We have investigated the effects of an applied current on the vortex dynamics in thin films of amorphous superconducting M${\mathrm{o}}_{77}$G${\mathrm{e}}_{23}$. At high currents, we see evidence of an ordering of the moving vortices in the flux flow regime. At lower currents and at very low temperatures, we see evidence of plastic and filamentary flow. We compare our data to recent theories of ordering and phase transitions in the moving vortex lattice.