Dramatically growing shear rigidity length scale in the supercooled glass former NiZr2

NB Weingartner and R Soklaski and KF Kelton and Z Nussinov, PHYSICAL REVIEW B, 93, 214201 (2016).

DOI: 10.1103/PhysRevB.93.214201

Finding a suitably growing length scale that increases in tandem with the immense viscous slowdown of supercooled liquids is an open problem associated with the glass transition. Here, we define and demonstrate the existence of one such length scale which may be experimentally verifiable. This is the length scale over which external shear perturbations appreciably penetrate into a liquid as the glass transition is approached. We provide simulation based evidence of its existence, and its growth by at least an order of magnitude, by using molecular dynamics simulations of NiZr2, a good fragile glass former. On the probed timescale, upon approaching the glass transition temperature T-g from above, this length scale xi is also shown to be consistent with Ising-like scaling, xi proportional to (T-T-g/T-g)(-nu), with nu approximate to 0.7. Furthermore, we demonstrate the possible scaling of xi about the temperature at which super-Arrhenius growth of viscosity, and a marked growth of the penetration depth, sets in. Our simulation results suggest that upon supercooling, marked initial increase of the shear penetration depth in fluids may occur in tandem with the breakdown of the Stokes-Einstein relation.

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