9730678 Marchetti Theoretical research will be conducted with the goal of understanding the dynamical properties of various spatially extended condensed matter systems. A major part of the research focusses on the nonequilibrium dynamics of periodic media driven through disorder. Examples of such systems include flux lattices in type-II superconductors, charge density waves in anisotropic conductors and the magnetically- induced Wigner crystal in a two-dimensional electron gas. As revealed by recent experiments, the interplay of interaction, disorder and drive results in a complex dynamics that is poorly understood. The main goals of this work are to develop a theoretical framework for the description of these nonequilibrium systems and to map out their nonequilibrium phase diagrams. Closely related problems that will also be investigated arise in microscopic models of friction and lubrication. One important difference is that inertial terms, negligible for overdamped systems such as flux lattices, may be important in this case and change the nature of the sliding state. A key objective is to understand the relative importance of surface roughness and bulk elasticity in yielding dissipation. Another effort more directly continues past research on flux- line arrays in type-II superconductors. The focus is on the physical consequences of entanglement and longtudinal correlations which are probed experimentally by magnetization measurements and transport experiments. Both analytical work, aiming at a two-fluid hydrodynamics capable of describing both entangled and disentangled components of flux liquid, and numerical work, addressing the stability of the transverse Meissner effect against point disorder, are described. %%% Theoretical research will be conducted on a class of problems which describe the behavior of the high temperature superconductors. These type of problems are very common and the results will also impact studies of friction, charge transport in periodic media and novel phases at low temperatues. ***
