Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session R3: Glass and Jamming TransitionsInvited

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Sponsoring Units: DCMP GSOFT GSNP Chair: Sydney Nagel, University of Chicago Room: Ballroom III 
Thursday, March 17, 2016 8:00AM  8:36AM 
R3.00001: The Gardner Transition: A new approach for understanding lowtemperature glasses Invited Speaker: Patrick Charbonneau Recent theoretical advances in the meanfield theory of glasses predict the existence deep in the glass phase of a novel phase transition, a socalled Gardner transition. This transition signals the emergence of a complex free energy landscape composed of a marginally stable hierarchy of subbasins within a broad glass metabasin. It is thus the onset of marked changes in thermal and transport properties of glasses, and ultimately leads to the unusual critical behavior at jamming. The Gardner transition itself is immediately related to a diverging (i) characteristic relaxation time, (ii) caging susceptibility and (iii) correlation length of the caging heterogeneity as well as aging, even in wellthermalized glasses. We have detected some of these signatures both in a meanfield model and in standard hardsphere glass formers. We find the results to quantitatively agree with theory in the former and qualitatively so in the latter, which suggest that the transition should be detectable in a wide array of numerical and experimental systems. Interestingly, although the Gardner transitions is primarily associated with structural glass formers, we also find features of the transition in crystals of polydisperse particles once the landscape becomes rough. [Preview Abstract] 
Thursday, March 17, 2016 8:36AM  9:12AM 
R3.00002: Scaling theory for the jamming transition Invited Speaker: Andrea J. Liu The existence of a critical jamming transition, which marks the onset of rigidity in athermal packings of spheres, suggests that universal physics underlies the origin and nature of rigidity in disordered solids ranging from glasses to foams and granular materials. The jamming transition was originally proposed as a zerotemperature critical point in a nonequilibrium phase diagram in packing density and shear stress. Many studies have documented critical phenomena near the jamming transition, including powerlaw scaling, diverging length scales and scaling collapse, and theories have been developed to understand these phenomena. However, a number of confusing features have precluded a unified critical scaling analysis of the transition. Here we resolve these issues to present a scaling ansatz for the jamming critical point in terms of density and shear stress. The theory predicts new exponents that we verify with numerical simulations. [Preview Abstract] 
Thursday, March 17, 2016 9:12AM  9:48AM 
R3.00003: Frustration by ShapeDesigned Local Polymorphism: A NearEquilibrium Colloidal Glass of Hard Kites Invited Speaker: Thomas Mason We study glass formation in uniform Brownian dispersions of hard colloidal polygonal platelets having the shape of 72degree achiral kites, fabricated using optical stepper lithography. These kites are confined to a plane through roughnesscontrolled depletion attractions, and they diffuse in twodimensions as we very slowly raise the particle density in the system. Although the densest packing of these kites is a crystalline lattice that fully tiles the plane, remarkably, we observe that the kites do not crystallize even for such quasistatic osmotic compression. By contrast, we have previously shown that such slow compression does cause crystallization of Brownian systems of other convex 2D lithographic shapes, such as squares and rhombs. Instead, the system of kites forms a disordered glass that undergoes an ergodic to nonergodic transition, both in a rotational and a translational sense, while remaining nearequilibrium, as we measure by video particle tracking. We show that the high diversity of fewparticle local polymorphic configurations (LPCs) of kites, related to our choice of angles and lengths in the designed shape, is responsible for suppressing long range spatial order and consequently favors glass formation instead. The prevalence and diversity of 5particle LPCs, such as the pentagonal star, frustrate crystallization because these pentagonal LPCs are topologically different than the one 4particle LPC that corresponds to the spacefilling crystal. We anticipate that this mechanism of glass formation through shapedependent frustration by diverse and incommensurate LPCs will also be relevant for molecular systems in three dimensions. [Preview Abstract] 
Thursday, March 17, 2016 9:48AM  10:24AM 
R3.00004: Solution of the dynamcs of highdimensional liquids Invited Speaker: jorge kurchan The dynamics of a liquid composed of particles with spherically symmetric potentials has been solved exactly in limit of high dimensions d. The calculation is long but straightforward. At high density, an ergodicitybreaking glass transition is found. This computation allows one to assess the validity of approximation schemes such as ModeCoupling Theory. As a byproduct, because our calculation is, if not rigorous, elementary, an improvement in the bound for sphere packings in large dimensions is now at hand. [Preview Abstract] 
Thursday, March 17, 2016 10:24AM  11:00AM 
R3.00005: Spinodals with Disorder: from Avalanches in Random Magnets to Glassy Dynamics Invited Speaker: Giulio Biroli We revisit the phenomenon of spinodals in the presence of quenched disorder and develop a complete theory for it. We focus on the spinodal of an Ising model in a quenched random field (RFIM), which has many applications in many areas from materials to social science. By working at zero temperature in the quasistatically driven RFIM, thermal fluctuations are eliminated and one can give a rigorous content to the notion of spinodal. We show that the spinodal transition is due to the depinning and the subsequent expansion of rare droplets. We work out the critical behavior, which, in any finite dimension, is very different from the meanfield one: the characteristic length diverges exponentially and the thermodynamic quantities display very mild nonanalyticities much like in a Griffith phenomenon. Thanks to the recently established connection between the spinodal of the RFIM and glassy dynamics, our results allow us to conclusively assess the physical content and the status of the dynamical transition predicted by the meanfield theory of glassforming liquids. [Preview Abstract] 
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