Global memory from local hysteresis in an amorphous solid

The atoms or particles within amorphous solids---like metallic glass or ice cream---tend to get stuck in one of many possible disordered arrangements. The authors explain a memory behavior in these materials by showing experimentally how one such material recalls past arrangements and thereby reports the magnitudes of past deformations. The memory emerges from the hysteresis of individual rearranging regions, and is similar to the return-point memory that is best known in ferromagnets---despite crucial differences in these materials' physics.