Driven Disordered Periodic Media with an Underlying Structural Phase Transition
Gautam I. Menon
Institute of Mathematical Sciences, Chennai, India
Mon, Jun. 16th 2008, 14:15
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
I summarize our recent work investigating the driven states of a two-dimensional crystal whose ground state can be tuned through a square-triangular transition. The depinning of such a system from a quenched random background potential occurs via a complex sequence of dynamical states, which include plastic flow states, hexatics, dynamically stabilized triangle and square phases and intermediate regimes of phase coexistence. These results are relevant to transport experiments in the mixed phase of several superconductors which exhibit such structural transitions, as well as to driven colloidal systems whose interactions can be tuned via surface modifications. They also raise several questions for theory, concerning, in particular, the possibility of dynamic phase coexistence in driven disordered systems. I will also discuss the connection to the peak effect in the vortex state of superconductors, an old yet little understood problem.