Critical Behavior of RIT Driven by Particle Density as Well as Shear Amplitude

In this chapter, we study a reversible-irreversible transition (RIT), where a periodically sheared many-particle system changes from time-periodic to diffusive phases accompanied by a diverging relaxation time with increasing shear amplitude. We study RIT driven by particle (vortex) density as well as shear amplitude. The critical behaviors of RIT are identical in all experiments, which proves new universalities of RIT. Two distinct flow regimes, corresponding to point-reversible and loop-reversible states, are found for the first time in the reversible phase. Surprisingly, we find the same critical behavior of RIT at the same critical point in either reversible regime.