Inverse Bauschinger effect in active ultrastable glasses.

Abstract

Memory effects in amorphous materials have been widely studied because of their possible widespread future applications. We show here that ultrastable glasses can exhibit a transient reversible memory effect when subjected to both a local driving force via run-and-tumble active particles and global shear. We investigate the system's response across different yielding regimes by selectively switching the shear direction at different strains. We analyze how changes in shear direction influence yielding, postyield behavior, and structural evolution in active amorphous solids. Our model active system exhibits an enhanced anisotropic response, displaying both conventional and inverse Bauschinger effects, depending on the deformation history. The results indicate that activity-induced shear band networks create structural memory, enabling the system to heal upon shear reversal due to the transient nature of this phenomenon. Additionally, shear softening under cyclic loading produces irreversible and less branched networks with increasing cycles, a structural evolution underlying the transition from inverse Bauschinger effect to conventional Bauschinger effect. These findings provide novel insights into how activity and shear collectively contribute to mechanical response, including memory formation in ultrastable disordered systems.