Itamar Procaccia (Weizmann Institute of Science)

Anomalous Elasticity and Emergent Dipole Screening in Amorphous Solids

Abstract: I will review our recent work in which  we developed a screening theory for describing the effect of plastic events in amorphous solids on their emergent mechanics. The suggested theory uncovered an anomalous mechanical response of amorphous solids where plastic events collectively induce distributed dipoles that are analogous to dislocations in crystalline solids. Classical elasticity is unable to predict the observed phenomena, and a fresh theory needs to be derived and solved.  The new physics is accompanied by translational symmetry breaking AND Chiral symmetry breaking, introducing unexpected length scales that cannot exist in classical elasticity theory, The theory was tested against various strain protocols of amorphous solids in two and three dimensions, including frictional and friction-less granular media and numerical models of amorphous glass.  I will conclude by interpreting the mechanical response as the formation of non-topological distributed dipoles that have no analogue in the crystalline defects literature. Having in mind that the onset of dipole screening is reminiscent of Kosterlitz-Thouless and Hexatic
transitions, the finding of dipole screening in three-dimensions is particularly novel.

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