Anomalous Elasticity in Amorphous Solids: Screening by plasticity

This colloquium will be given in-person and in parallel through Zoom: https://technion.zoom.us/j/92789918170. 

Abstract:

In this Lecture I will review some recent work in which it was shown that mechanical strains in amorphous solids are screened by the formation of plastic events that are typically quadrupolar in nature. At low densities the screening effect is reminiscent of the role of dipoles in dielectrics, while the effect at high density has no immediate electrostatic analog, and is shown to change qualitatively the form of elasticity theory, as seen for example in the observed displacement fields. High-density screening results in an undulating displacement field that strictly deviates from elasticity theory. I will argue that theoretical analysis, experimental measurements and numeric simulations of a variety of amorphous solids are in agreement with each other and provide support for the novel theory. Finally I will explain the relation of the present findings to the Kosterlitz-Thouless transition and to the Hexatic phase of two dimensional melting.