Isothermal-expansion melting of two-dimensional colloidal monolayers on the surface of water

Armstrong, A. J.; Mockler, R. C.; O'Sullivan, W.J.

doi:10.1088/0953-8984/1/9/015

Cited by 74 publications

(46 citation statements)

References 36 publications

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“…In this scenario, the two phase transitions (crystal-tohexatic and hexatic-to-fluid) are predicted to be of second order, driven by the unbinding of different types of topological defects (dislocations and disclinations) [2,3]. However, after many decades of experimental and numerical research, evidence was collected that several 2D systems fall outside KTHNY theory, melting in a single first order transition, or in a two-step process by one first order and one continuous transitions [4][5][6]. While the characterization of melting transitions of 2D crystals is a long-standing problem that has received great attention, almost all the effort has been focused on simple potentials forming simple crystals, with only a few numerical studies available on the generalized exponential model [7,8].…”

Section: Introductionmentioning

confidence: 99%

Melting of a two-dimensional monodisperse cluster crystal to a cluster liquid

et al. 2019

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Monodisperse ensembles of particles that have cluster crystalline phases at low temperatures can model a number of physical systems, such as vortices in type-1.5 superconductors, colloidal suspensions and cold atoms. In this work we study a two-dimensional cluster-forming particle system interacting via an ultrasoft potential. We present a simple mean-field characterization of the cluster-crystal ground state, corroborating with Monte Carlo simulations for a wide range of densities. The efficiency of several Monte Carlo algorithms are compared and the challenges of thermal equilibrium sampling are identified. We demonstrate that the liquid to clustercrystal phase transition is of first order and occurs in a single step, and the liquid phase is a cluster liquid. arXiv:1812.01113v2 [cond-mat.soft]

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Section: Introductionmentioning

confidence: 99%

Melting of a two-dimensional monodisperse cluster crystal to a cluster liquid

et al. 2019

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“…In this scenario, the interparticle distance will depend only on the surface density of particles. Amstrong et al [11], using charge-stabilized colloidal particles, performed careful experiments at high surface densities to study two-dimensional melting. They found evidence of defect-mediated melting and of the appearance of a hexatic phase.…”

Section: Introductionmentioning

confidence: 99%

Computer simulations of confined colloidal systems at the air/water interface

Mejía-Rosales

Gil‐Villegas

Ruíz-García

2002

J. Phys.: Condens. Matter

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We present Monte Carlo simulations in the NV T ensemble for spherical particles of diameter σ interacting via a hard-core potential with a squareshoulder (SS) repulsive barrier, a square-well (SW) attraction, and a second SS repulsion. This discrete potential is used to mimic the pair interaction in confined colloidal systems at the air/water interface. The SW attraction represents a secondary minimum for large interparticle distances, and the SS repulsion is a shallow secondary maximum after the secondary minimum. The effect of the SS range λ r σ is studied for the cases λ r = 0, 6, and 7. The simulation results for the last two cases indicate the important role of the presence of the secondary maximum in the interaction potential, since they are able to reproduce the main features observed in colloidal particles trapped at the air/water interface, such as clustering, chain formation, foams, and the presence of voids.

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“…Whereas three-dimensional (3D) solids characteristically exhibit first order (or discontinuous) melting transitions, 2D solids can melt by either continuous or first order melting transitions and may exhibit an intermediate, so-called "x-atic" ordered phase that is somewhere between a fluid and a solid. Previous studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] that examine two-dimensional melting find three distinct scenarios [19,20]. One, the system can exhibit a continuous fluid-to-x-atic-to-solid transition.…”

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Shape and Symmetry Determine Two-Dimensional Melting Transitions of Hard Regular Polygons

et al. 2017

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The melting transition of two-dimensional systems is a fundamental problem in condensed matter and statistical physics that has advanced significantly through the application of computational resources and algorithms. Two-dimensional systems present the opportunity for novel phases and phase transition scenarios not observed in 3D systems, but these phases depend sensitively on the system and, thus, predicting how any given 2D system will behave remains a challenge. Here, we report a comprehensive simulation study of the phase behavior near the melting transition of all hard regular polygons with 3 ≤ n ≤ 14 vertices using massively parallel Monte Carlo simulations of up to 1 × 10 6 particles. By investigating this family of shapes, we show that the melting transition depends upon both particle shape and symmetry considerations, which together can predict which of three different melting scenarios will occur for a given n. We show that systems of polygons with as few as seven edges behave like hard disks; they melt continuously from a solid to a hexatic fluid and then undergo a first-order transition from the hexatic phase to the isotropic fluid phase. We show that this behavior, which holds for all 7 ≤ n ≤ 14, arises from weak entropic forces among the particles. Strong directional entropic forces align polygons with fewer than seven edges and impose local order in the fluid. These forces can enhance or suppress the discontinuous character of the transition depending on whether the local order in the fluid is compatible with the local order in the solid. As a result, systems of triangles, squares, and hexagons exhibit a Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) predicted continuous transition between isotropic fluid and triatic, tetratic, and hexatic phases, respectively, and a continuous transition from the appropriate x-atic to the solid. In particular, we find that systems of hexagons display continuous two-step KTHNY melting. In contrast, due to symmetry incompatibility between the ordered fluid and solid, systems of pentagons and plane-filling fourfold pentilles display a one-step first-order melting of the solid to the isotropic fluid with no intermediate phase.

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Isothermal-expansion melting of two-dimensional colloidal monolayers on the surface of water

Cited by 74 publications

References 36 publications

Melting of a two-dimensional monodisperse cluster crystal to a cluster liquid

Melting of a two-dimensional monodisperse cluster crystal to a cluster liquid

Computer simulations of confined colloidal systems at the air/water interface

Shape and Symmetry Determine Two-Dimensional Melting Transitions of Hard Regular Polygons

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