Kovacs like memory effect under volume conserving deformation

Maitri Mandal, Abhishek Ghadai, Rituparno Mandal and Sayantan Majumdar

Systems which are far from equilibrium state can exhibit memory effect. Memory study can reveal hidden physical properties of the system which is helpful to design smart materials. Kovacs Effect is one kind of memory effect observed in glassy systems where system remembers duration of a perturbation. When the system undergoes two step perturbations, after the 2nd perturbation its response shows non-monotonic behaviour. But under volume preserving mechanical deformation, like shear, the phenomena remain unexplored. We find such non-monotonic stress relaxation under shear deformation in a dense aqueous suspension of soft colloidal particles. We also verified as long as the perturbation is small, peak of the nonmonotonic stress relaxation can be predicted by a recent proposed theorem. Furthermore, through boundary imaging we can correlate system’s microstructural changes during perturbation with deviations from predictions.