Abstract
Disks of equal size should readily fit together to form a crystal. In reality, it happens very infrequently! Any minor hiccup, particularly from friction, can disrupt the neat order, leaving us with an arrangement of polycrystals. It would be interesting to know how to anneal such polycrystals into a single crystal. In this talk, I will demonstrate how this can be achieved. Under the effect of oscillatory shear, a monolayer of frictional granular disks can undergo two phase transitions: a transition from an initially disordered state to an ordered crystalline form, and a dynamic active-absorbing phase transition. Although there is no obvious reason for them to be at the same critical point, they are. The transitions may also be characterized by the disk trajectories, which are nontrivial loops breaking time-reversal invariance.
Brief Biosketch:
Prof. Ghosh trained as an experimental physicist. He did his PhD from IISc in 2005 and since then he has been a faculty at TIFR. He was awarded the Shanti Swarup Bhatnagar Award in 2019.