Absence of translational ordering in driven vortex lattices

By using finite-temperature molecular-dynamics simulations, we consider the question of the existence of dynamical ordering as a two-dimensional vortex lattice is driven through a random background potential. The shape of the current-voltage (I-V) characteristics are qualitatively the same as those seen in experiments on the conventional superconductors 2H-${\mathrm{NbSe}}_2$ and ${\mathrm{Mo}}_{77}$ ${\mathrm{Ge}}_{23}$. However, in contrast to previous simulations, we find that the lattice has no topological or translational order for any value of the driving but that it does exhibit a high driving phase where long-range orientational order exists.