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Full-Text Articles in Physics
Nematic Textures In Spherical Shells, Vincenzo Vitelli, David R. Nelson
Nematic Textures In Spherical Shells, Vincenzo Vitelli, David R. Nelson
David R. Nelson
The equilibrium texture of nematic shells is studied as a function of their thickness. For ultrathin shells the ground state has four short ½ disclination lines but, as the thickness of the film increases, a three-dimensional escaped configuration composed of two pairs of half-hedgehogs becomes energetically favorable. We derive an exact solution for the nematic ground state in the one Frank constant approximation and study the stability of the corresponding texture against thermal fluctuations.
Vortex Physics In Confined Geometries, M. Cristina Marchetti, David R. Nelson
Vortex Physics In Confined Geometries, M. Cristina Marchetti, David R. Nelson
David R. Nelson
Patterned irradiation of cuprate superconductors with columnar defects allows a new generation of experiments which can probe the properties of vortex liquids by forcing them to flow in confined geometries. Such experiments can be used to distinguish experimentally between continuous disorder-driven glass transitions of vortex matter, such as the vortex glass or the Bose glass transition, and nonequilibrium polymer-like glass transitions driven by interaction and entanglement. For continuous glass transitions, an analysis of such experiments that combines an inhomogeneous scaling theory with the hydrodynamic description of viscous flow of vortex liquids can be used to infer the critical behavior. After …
Extrinsic Curvature, Geometric Optics, And Lamellar Order On Curved Substrates, Randall D. Kamien, David R. Nelson, Christian D. Santangelo, Vincenzo Vitelli
Extrinsic Curvature, Geometric Optics, And Lamellar Order On Curved Substrates, Randall D. Kamien, David R. Nelson, Christian D. Santangelo, Vincenzo Vitelli
David R. Nelson
When thermal energies are weak, two-dimensional lamellar structures confined on a curved substrate display complex patterns arising from the competition between layer bending and compression in the presence of geometric constraints. We present broad design principles to engineer the geometry of the underlying substrate so that a desired lamellar pattern can be obtained by self-assembly. Two distinct physical effects are identified as key factors that contribute to the interaction between the shape of the underlying surface and the resulting lamellar morphology. The first is a local ordering field for the direction of each individual layer, which tends to minimize its …