192 research outputs found

    Replica theory of the rigidity of structural glasses

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    We present a first principle scheme to compute the rigidity, i. e. the shear-modulus of structural glasses at finite temperatures using the cloned liquid theory, which combines the replica theory and the liquid theory. With the aid of the replica method which enables disentanglement of thermal fluctuations in liquids into intra-state and inter-state fluctuations, we extract the rigidity of metastable amorphous solid states in the supercooled liquid and glass phases. The result can be understood intuitively without replicas. As a test case, we apply the scheme to the supercooled and glassy state of a binary mixture of soft-spheres. The result compares well with the shear-modulus obtained by a previous molecular dynamic simulation. The rigidity of metastable states is significantly reduced with respect to the instantaneous rigidity, namely the Born term, due to non-affine responses caused by displacements of particles inside cages at all temperatures down to T=0. It becomes nearly independent of temperature below the Kauzmann temperature T_K. At higher temperatures in the supercooled liquid state, the non-affine correction to the rigidity becomes stronger suggesting melting of the metastable solid state. Inter-state part of the static response implies jerky, intermittent stress-strain curves with static analogue of yielding at mesoscopic scales.Comment: 52 pages, 10 figure

    Disorder-free spin glass transitions and jamming in exactly solvable mean-field models

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    We construct and analyze a family of MM-component vectorial spin systems which exhibit glass transitions and jamming within supercooled paramagnetic states without quenched disorder. Our system is defined on lattices with connectivity c=Ξ±Mc=\alpha M and becomes exactly solvable in the limit of large number of components Mβ†’βˆžM \to \infty. We consider generic pp-body interactions between the vectorial Ising/continuous spins with linear/non-linear potentials. The existence of self-generated randomness is demonstrated by showing that the random energy model is recovered from a MM-component ferromagnetic pp-spin Ising model in Mβ†’βˆžM \to \infty and pβ†’βˆžp \to \infty limit. In our systems the quenched disorder, if present, and the self-generated disorder act additively. Our theory provides a unified mean-field theoretical framework for glass transitions of rotational degree of freedoms such as orientation of molecules in glass forming liquids, color angles in continuous coloring of graphs and vector spins of geometrically frustrated magnets. The rotational glass transitions accompany various types of replica symmetry breaking. In the case of repulsive hardcore interactions in the spin space, continuous the criticality of the jamming or SAT/UNSTAT transition becomes the same as that of hardspheres.Comment: 85 pages (9 figures) Revised and extended version submitted to SciPost Physics. (Analysis on anisotropic particles included in v2 will be presented in a separate publication.

    Rigidity of glasses and jamming systems at low temperatures

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    We discuss a microscopic scheme to compute the rigidity of glasses or the plateau modulus of supercooled liquids by twisting replicated liquids. We first summarize the method in the case of harmonic glasses with analytic potentials. Then we discuss how it can be extended to the case of repulsive contact systems : the hard sphere glass and related systems with repulsive contact potentials which enable the jamming transition at zero temperature. For the repulsive contact systems we find entropic rigidity which behaves similarly as the pressure in the low temperature limit: it is proportional to the temperature and tends to diverge approaching the jamming density with increasing volume fraction, which may account for experimental observations of rigidities of repulsive colloids and emulsions.Comment: 8 pages, submitted to AIP conference proceedings for "Slow Dynamics in Complex Systems" (Sendai, Japan, Dec. 2012
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