Competing phases and driving though jam in a superconductor

A liquid phase of matter when cooled can either crystallize below its freezing temperature into a crystalline solid or can be supercooled into a glassy state.  Investigation into the perplexing properties of the glassy state is one of the oldest branches of study in condensed matter physics. Though far removed from the behaviour of conventional glasses, surprisingly the vortex state in a realistic type II superconductor also exhibits glassy behaviour. During my talk, I will touch upon the role of disorder, and the identification of metastabilty, aging phenomenon in vortex glass state which are features found even in conventional glassy systems. Recent results on the competition between different glassy vortex phases will also be presented [1]. Another interesting property is the nature of the moving vortex state under the influence of drive. It is worthwhile asking, do the intervortex correlations and the underlying phase transition between the different static glassy vortex states survive in the driven vortex state, and what is nature of vortex flow? Theoretically and experimentally different regimes of flow of the vortex state have been identified. Our recent investigations (IIT K, TIFR and IISc. collaboration) have revealed the onset of jam in the driven vortex state, which appears to be a favoured configuration in the moving state [2, 3]. We have identified some of the protocols producing this jam. The jamming - unjamming transformation in the driven vortex state leads to a new fluctuating phase sandwiched between two relatively quiescent vortex states and the fluctuating regime is associated with critical like behaviour akin to equilibrium critical phase transition phenomenon. The statistics of fluctuations in the jammed vortex state are also novel and reveal events of vortices drifting in a direction opposite to the drive. Such events have also been recently reported in jamming phenomenon in other soft systems. 
[1] Shyam; Mohan, Jaivardhan Sinha, S. S. Banerjee, Yuri Myasoedov, Phys. Rev. Lett. 98, 027003 (2007). 
[2] Shyam Mohan, Jaivardhan Sinha, and S. S. Banerjee, A.K. Sood, S. Ramakrishnan and A. K. Grover, Phys. Rev. Lett. 103, 167001 (2009).
[3] Gorky Shaw, Pabitra Mandal, S. S. Banerjee, A. Niazi, A. K. Rastogi, A. K. Sood, S. Ramakrishnan and A. K. Grover, Jamming, un-jamming and critical behaviour in driven vortex state (submitted)