Global Memory from Local Hysteresis in an Amorphous Solid

Understand

A disordered material that cannot relax to equilibrium, such as an amorphous or glassy solid, responds to deformation in a way that depends on its past.

• In experiments we train a 2D athermal amorphous solid with oscillatory shear, and show that a suitable readout protocol reveals the shearing amplitude.
• When shearing alternates between two amplitudes, signatures of both values are retained only if the smaller one is applied last.
• We show that these behaviors arise because individual clusters of rearrangements are hysteretic and dissipative, and because different clusters respond differently to shear.