Dynamic vortex ordering in thin a-Nb70Ge30 films - art. no. 094511

We investigated ordering of the vortex lattice under the influence of a dri ving current in amorphous superconducting films of Nb70Ge30 with varying am ounts of disorder. Using the nonlinear behavior of the voltage versus curre nt relations, i.e., the peak in the dynamical resistance, we map the occurr ence of this dynamical ordering (DO) in the (B,T) phase diagram. Using the collective pinning analysis, DO is shown to appear when the size of the cor related regions drops below the order of approximate to ten times the vorte x lattice distance. This means that for weaker intrinsic disorder, DO moves closer to the melting line. The current at which DO occurs diverges at the melting transition, in agreement with the notion that increasing velocitie s are needed to overcome the effect of either temperature or softening of t he shear modulus of the vortex lattice.