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Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Population Annealing Monte Carlo Studies Of Ising Spin Glasses, Wenlong Wang
Population Annealing Monte Carlo Studies Of Ising Spin Glasses, Wenlong Wang
Doctoral Dissertations
Spin glasses are spin-lattice models with quenched disorder and frustration. The mean field long-range Sherrington-Kirkpatrick (SK) model was solved by Parisi and displays replica symmetry breaking (RSB), but the more realistic short-range Edwards-Anderson (EA) model is still not solved. Whether the EA spin glass phase has many pairs of pure states as described by the RSB scenario or a single pair of pure states as described by two-state scenarios such as the droplet/scaling picture is not known yet. Rigorous analytical calculations of the EA model are not available at present and efficient numerical simulations of spin glasses are crucial in …
Elasticity And Geometry In Curved-Filament Assemblies, Luis Cajamarca Ospina
Elasticity And Geometry In Curved-Filament Assemblies, Luis Cajamarca Ospina
Doctoral Dissertations
In this dissertation we explore the effect of shape, mechanics and geometry in assemblies of tubular filaments by introducing the notion of cohesive contact. We first study the optimal geometry of cohesive interactions in straight flexible tubes by considering two interaction potentials. We find filaments adopt a locally skewed configuration, associated with a twist angle. The interaction energy decreases with the twist angle and ground states are found to be twisted. For pair-wise interactions, we find a generic behavior in the profile of the cohesive energy where the geometry of close-packed double helices dictates the shape of the assembly. By …
Emergent Structure Of Multi-Dislocation Ground States In Frustrated Assemblies, Amir Azadi
Emergent Structure Of Multi-Dislocation Ground States In Frustrated Assemblies, Amir Azadi
Doctoral Dissertations
In this dissertation we study the emergent patterns of multi-dislocation ground states in two geometrically related classes of frustrated assemblies, twisted filament bundles and crystalline spherical cap. We discuss the fundamental role played by characteristic patterns of dislocations in restructuring the ordered phase of theses geometrically frustrated systems in the presence of external stresses. Our analysis on the formation of grain boundary scars leads to universal predictions for the features of defect patterns and their underlying energetic principles.
Magnetic Transport Properties Of Oriented Soft, Hard And Exchange-Coupled Magnetic Thin Films And Au25(Sc6H13)18 Spherical Nanocluster, Rukshan M. Thantirige
Magnetic Transport Properties Of Oriented Soft, Hard And Exchange-Coupled Magnetic Thin Films And Au25(Sc6H13)18 Spherical Nanocluster, Rukshan M. Thantirige
Doctoral Dissertations
This study was conducted with the aim of improving permanent magnetic properties of existing materials and exploring non-conventional ferromagnetic properties of gold-based nanoclusters. The first chapter of this dissertation gives an introduction to relevant fundamental concepts and proceeding chapters present findings of three projects. In the first project, shape anisotropy induced permanent magnetism in oriented magnetic thin films was investigated. Roll-to-roll nanoimprinting, a high-throughput fabrication method was utilized to fabricate densely packed Fe nanostripe-based magnetic thin films that exhibit large in-plane uniaxial anisotropy and nearly square hysteresis loops at room temperature. (BH)max exceeds 3 MGOe for samples of intermediate …
Mechanics Of Helical And Fabric-Like Mesostructures From Polymer-Nanoparticle Hybrids, Jonathan T. Pham
Mechanics Of Helical And Fabric-Like Mesostructures From Polymer-Nanoparticle Hybrids, Jonathan T. Pham
Doctoral Dissertations
Hierarchical structures developed from nanoscale building blocks offer an excellent opportunity to control properties on all length scales, from the molecular level up to the macroscale. Many beautiful examples in Nature have demonstrated the significance of controlling geometry and mechanics on small length scales to control function on an organism-level, shown by the strength of bones, the toughness of a mollusk's shell, or the gecko's ability to climb walls. Inspired by stunning examples in both Nature and common man-made materials and structures, we assemble polymers and inorganic nanoparticles (NPs) with well-defined surface chemistry into long ribbons and fabric-like networks with …