Defect-mediated relaxation in the random tiling phase of a binary mixture: Birth, death and mobility of an atomic zipper

Tondl, Elisabeth; Ramsay, Malcolm; Harrowell, Peter; Widmer‐Cooper, Asaph

doi:10.1063/1.4867388

Cited by 3 publications

(2 citation statements)

References 42 publications

(53 reference statements)

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“…Recent simulation studies [72] of the ST2 model of water [80] have shown that the FS crossover can be described in terms of the concentration of defects in the network, while similar results have been obtained for network forming colloids [81] and nanoparticles [82]. The structural relaxation of a two-dimensional random tiling model has also been described in terms of defect motion [83]. These studies suggest that understanding how defects effect structural relaxation may provide insight to the dynamics of amorphous systems.…”

Section: Discussionmentioning

confidence: 63%

Inherent structures, fragility, and jamming: Insights from quasi-one-dimensional hard disks

2015

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We study a quasi-one-dimensional system of hard disks confined between hard lines to explore the relationship between the inherent structure landscape, the thermodynamics, and the dynamics of the fluid. The transfer matrix method is used to obtain an exact description of the landscape, equation of state, and provide a mapping of configurations of the equilibrium fluid to their local jammed structures. This allows us to follow how the system samples the landscape as a function of occupied volume fraction ϕ. Configurations of the ideal gas map to the maximum in the distribution of inherent structures, with a jamming volume fraction ϕ(J)(*), and sample more dense basins with increasing ϕ. This suggests jammed states with a density below ϕ(J)(*) are inaccessible from the equilibrium fluid. The configurational entropy of the fluid decreases rapidly at intermediate ϕ before plateauing at a low value and going to zero as the most dense packing is approached. This leads to the appearance of a maximum in both the isobaric heat capacity and the inherent structure pressure. We also show that the system exhibits a crossover from fragile to strong fluid behavior, located at the heat capacity maximum. Structural relaxation in the fragile fluid is shown to be controlled by the presence of high order saddle points caused by neighboring defects that are unstable with respect to jamming and spontaneously rearrange to form a stable local environment. In the strong fluid, the defect concentration is low so that defects do not interact and relaxation occurs through the hopping of isolated defects between stable local packing environments.

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Section: Discussionmentioning

confidence: 63%

Inherent structures, fragility, and jamming: Insights from quasi-one-dimensional hard disks

2015

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“…the formation of cracks, which is in striking contrast to the behaviour of one-component crystals near melting [36]. Furthermore, the breakage of the thermal binary crystal resembles the plastic deformation of amorphous materials [50][51][52][53][54][55][56][57], where, due to the absence of distinct topological defects, plastic deformation is mediated by localized patterns of nonaffine motion [52,[58][59][60][61][62][63][64] and can be traced by the inherent stress signature and spatial correlation of plastic events [65][66][67] or contact force distributions [68]. Our results are verifiable in real-space experiments of superparamagnetic colloidal mixtures at a pending air-water interface in an external magnetic field [69][70][71][72][73], where the shear can be induced by an external laser field.…”

Section: Introductionmentioning

confidence: 99%

How does a thermal binary crystal break under shear?

Horn

Löwen

2014

The Journal of Chemical Physics

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When exposed to strong shearing, the particles in a crystal will rearrange and ultimately, the crystal will break by forming large nonaffine defects. Even for the initial stage of this process, only little effort has been devoted to the understanding of the breaking process on the scale of the individual particle size for thermalized mixed crystals. Here, we explore the shear-induced breaking for an equimolar two-dimensional binary model crystal with a high interaction asymmetry between the two different species such that the initial crystal has an intersecting square sublattice of the two constituents. Using Brownian dynamics computer simulations, we show that the combination of shear and thermal fluctuations leads to a characteristic hierarchical breaking scenario where initially, the more strongly coupled particles are thermally distorted, paving the way for the weakly coupled particles to escape from their cage. This in turn leads to mobile defects which may finally merge, proliferating a cascade of defects, which triggers the final breakage of the crystal. This scenario is in marked contrast to the breakage of one-component crystals close to melting. Moreover, we explore the orientational dependence of the initial shear direction relative to the crystal orientation and compare this to the usual melting scenario without shear. Our results are verifiable in real-space experiments of superparamagnetic colloidal mixtures at a pending air-water interface in an external magnetic field where the shear can be induced by an external laser field.

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Growth of two-dimensional dodecagonal colloidal quasicrystals: Particles with isotropic pair interactions with two length scales vs. patchy colloids with preferred binding angles

2018

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Defect-mediated relaxation in the random tiling phase of a binary mixture: Birth, death and mobility of an atomic zipper

Cited by 3 publications

References 42 publications

Inherent structures, fragility, and jamming: Insights from quasi-one-dimensional hard disks

Inherent structures, fragility, and jamming: Insights from quasi-one-dimensional hard disks

How does a thermal binary crystal break under shear?

Growth of two-dimensional dodecagonal colloidal quasicrystals: Particles with isotropic pair interactions with two length scales vs. patchy colloids with preferred binding angles

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