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Addressing the protocol dependence of glass plasticity and yielding
The glassy slowdown is a phenomenon whereupon a liquid, when supercooled below its melting point, exhibits a dramatic slowdown of its dynamics, such that it rapidly becomes impossible to maintain it equilibrated on feasible experimental timescales. The resulting out-of-equilibrium system is referred to as a glass, and exhibits but unremarkable structural changes with respect to the melt it was made from.
A commonly accepted theory of this slowdown is at the moment missing. Early efforts focused on finding a fitting form for the viscosity vs. temperature curve of the supercooled liquid, which is however hard to test experimentally at low temperatures due to the slowdown. In this talk I will argue in favor of a shift in perspective from the equilibrium supercooled liquid to the out-of-equilibrium glass, and in favor of studying the plasticity and yielding phenomena of these systems as a way to look for universal, robust measurements that can potentially serve as a test-bed for theories of the glassy slowdown.
An essential part of such a program is to devise a scheme to treat the dependence on preparation history that metastable glasses are automatically endowed with as out-of-equilibrium systems ;
a proposal for such a scheme, linked to the phenomenon of sound attenuation in amorphous media, is presented.