One emphasis of our work is to understand the properties of disordered materials. Such materials have many common features that are different from their crystalline counterparts. By varying some external parameter, these materials can become structurally arrested - that is they jam. We are interested in understanding what controls the onset of rigidity in a wide variety of situations. Do all jammed systems have a common set of inherent properties? If so, can we learn about the nature of glasses (where the ability to flow has been lost when the temperature is dropped to too low a value) by studying the jamming that occurs in a granular material such as a sand pile as it suddenly stops flowing?

In an effort to deal with diverse phenomena where systems become stuck in a region far from equilibrium (e.g., at the glass transition and in clogged granular materials flowing - unsuccessfully - through a pipe), we have been investigating, in collaboration with Professor Andrea Liu at The University of Pennsylvania, whether there can be a more general way of looking at these systems in terms of a Jamming Phase Diagram. Such a concept would relate the physics of granular materials with those of glasses.

“Jamming in finite systems: Stability, anisotropy, fluctuations, and scaling,” C. P. Goodrich, S. Dagois-Bohy, B. P. Tighe, M. van Hecke, A. J. Liu, and S. R. Nagel, Phys. Rev. E., 90, 022138 (2014).

“Collision Dynamics of Particle Clusters in a Two-dimensional Granular Gas,” Justin C. Burton, Peter Y. Lu, and S. R. Nagel, Phys. Rev. E., 88, 062204 (2013).

“Comment on “Repulsive Contact Interactions Make Jammed Particulate Systems Inherently Nonharmonic”,” C. P. Goodrich, A. J. Liu, and S. R. Nagel, Phys. Rev. Lett., 112, 049801 (2013). arXiv:1306.1285

“Energy Loss at Propagating Jamming Fronts in Granular Gas Clusters,” J. C. Burton, P. Y. Lu, and S. R. Nagel, Phys. Rev. Lett. 111, 188001 1-4 (cover illustration) (2013).

“Stability of jammed packings II: the transverse length scale,” S. S. Schoenholz, C. P. Goodrich, O. Kogan, A. J. Liu and S. R. Nagel, Soft Matter 9, 11000-11006 (2013).

“Observation and Characterization of the Vestige of the Jamming Transition in a Thermal 3D System”, Thomas A Caswell, Zexin Zhang, Margaret L Gardel, and Sidney R Nagel, Phys. Rev. E 87, 012303 (2013).

“Finite-Size Scaling at the Jamming Transition”, C. P. Goodrich, A. J. Liu and S.R. Nagel Phys. Rev. Lett. 109, 095704 (2012).

“Glassy Dynamics in thermally-activated list sorting”, L.-N. Zou, S.R. Nagel, Phys. Rev. Lett, 104 257201 1-4 (2010).

“Jamming”. A.J. Liu, and S.R. Nagel, Soft Matter, 6, 2869-2870 (2010). editorial for focus issue on Jamming. Guest editors: A.J. Liu and S.R. Nagel

“The jamming transition and the marginally jammed solid,” A. J. Liu and S. R. Nagel, Annual Reviews of Cond. Mat. Phys. 1, 14.1-14.23 (2010).

“Experimental study of the jamming transition at zero temperature”, X. Cheng, Phys. Rev. E, 81 031301 (2010).

“Anharmonicity and quasi-localization of the excess low-frequency vibrations in jammed solids,” N. Xu, V. Vitelli, A. J. Liu, and S. R. Nagel, Europhys. Lett., 90, 56001 1-6 (2010).

“Heat transport in model jammed solids,” V. Vitelli, N. Xu, M. Wyart, A. J. Liu, S. R. Nagel, Phys. Rev. E 81, 021301 1-14 (2010). arXiv:0908.2176

“Packing structure of a two-dimensional granular system through the jamming transition”, X. Cheng, Soft Matter, 6 2931 (2010).

“Thermal Vestige of the Zero-Temperature Jamming Transition,” Z. Zhang, N. Xu, D. T. N. Chen, P. Yunker, A. M. Alsayed, K. B. Aptowicz, P. Habdas, A. J. Liu, S. R. Nagel and A. G. Yodh, Nature 459, 230-233 (2009).

“Excitations of Ellipsoid Packings near Jamming,” Z. Zeravcic, N. Xu, A. J. Liu, S. R. Nagel and W. van Saarloos, Europhys. Lett. 87, 26001 (2009).

“The packing of granular polymer chains,” L.-N. Zou, X. Cheng, M. L. Rivers, H. M. Jaeger, S. R. Nagel, Science 326, 408-410(2009).

“Equivalence of glass transition and colloidal glass transition in the hard-sphere limit,” Ning Xu, T. K. Haxton, A. J. Liu, S. R. Nagel, Phys. Rev. Lett. 103, 245701 (2009).

“Normal modes in model jammed systems in three dimensions,” L. E. Silbert, A. J. Liu and S. R. Nagel, Phys. Rev. E 79, 021308 (2009).

“Energy transport in jammed sphere packings,” N. Xu, V. Vitelli, M. Wyart, A. J. Liu, S. R. Nagel, Phys. Rev. Lett. 102, 038001 (2009).

“Excess Vibrational Modes and the Boson Peak in Model Glasses,” N. Xu, M. Wyart, A. J. Liu and S. R. Nagel, Phys. Rev. Lett. 98, 175502 (2007).

“The compressible spin glass: Simulation results,” A. H. Marshall, Phys. Rev. B 75, 054414 (2007).

“Structural signatures of the unjamming transition at zero temperature,” L. E. Silbert, A. J. Liu, and S. R. Nagel, Phys. Rev. E 73, 041304 1-8 (2006).

“Vibrations and diverging length scales near the unjamming transition,” L. E. Silbert, A. J. Liu and S. R. Nagel, Phys. Rev. Lett. 95, 098301 1-4 (2005).

“Structural signature of jamming in granular media,” E. I. Corwin, H. M. Jaeger, and S. R. Nagel, Nature 435, 1075-1078 (2005).

“Effects of compression on the vibrational modes of marginally jammed solids,” M. Wyart, L. E. Silbert, S. R. Nagel and T. A. Witten, Phys. Rev. E 72, 051306 1-11 (2005).

“Numerical studies of the compressible Ising spin glass,” A. H. Marshall, S. R. Nagel and B. Chakraborty, Europhysics Lett. 74, 699-705 (2006)

Jammed systems

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