Critical dynamics and scaling in ultra-strong glassforming systems

"Ultra-strong" glassforming materials, characterized by sub-Arrhenius increases of the relaxation time with inverse temperature, have emerged as a category of recent interest. This unusual behavior has been observed in seemingly disparate computational systems: geometric models of dense biological tissue, low-density vitrimeric systems, and thermalized hard spheres below jamming. What, if anything, connects the structure and dynamics of these models, and what are the necessary ingredients for ultra-strong phenomenology to emerge? In this talk I present evidence from our group's mechanical and rheological measurements demonstrating (1) a connection between the unusual elastic properties of the geometric cell models and their sub-Arrhenius dynamics, and (2) that the dynamics approach power-law relaxation dynamics. This is suggestive of critical phenomena (which appears to be controlled by a zero-temperature critical point) rather than the traditional activated processes seen in standard glasses. I will then discuss the relation between the sub-Arrhenius dynamics observed in the different computational models, with scaling plots that suggest that there may be different universality classes characterizing different ultra-strong glassforming systems. I will conclude by discussing ongoing work to measure the associated critical exponents and potential material properties in these systems.