Ph.D. (Doctor of Philosophy)
Department of Physics
There are many condensed matter problems which are too complicated for analytical solutions. Complex functions such as the Ginzburg-Landau equation for superconductors can not be studied analytically for mesoscopic phenomena. Similarly, a thorough understanding of variable range hopping in electrons requires a new Monte-Carlo algorithm. With this in mind we computationally study two cases of condensed matter physics, pinning vortices in superconductors and thermoelectrics in artificial nanosolids. Vortex-vortex interactions and vortex-inclusion interactions are not fully understood analytically. These analytical calculations become near-impossible when taken to mesoscopic scales. Applied temperature, magnetic field, or currents only serve to complicate the system. Yet these are all factors whose effects need to be well understood before large scale applications can be implemented. Here we report two geometry-based strategies, the effect of vortex-inclusion matching on the effective resistance, and a novel funnel system for jamming the vortices. Both of these strategies are designed to reduce energy dissipation by moving vortices. In the second part, we study thermoelectric effects in artificial nanosolids. To this end, a parallel optimized algorithm for simulation of variable-range hopping of electrons in nanosolids was designed and implemented. We exploit the similarities between granule hopping and electrons in a Coulomb glass to get a better analytical understanding. We benchmark this code using known analytical results in limiting cases. We then make predictions for Seebeck coefficients in mixed conductor-semiconductor granular nanosolids.
Viti, Ivan, "Simulations in multiphasic nanosolids and superconducting nanostructures" (2016). Graduate Research Theses & Dissertations. 4925.
x, 87 pages
Northern Illinois University
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