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Research Abstracts Online
January 2009 - March 2010

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University of Minnesota Twin Cities
Institute of Technology
School of Physics and Astronomy
Department of Physics

PI: Oriol T. Valls, Fellow

Numerical Studies on Superconducting Proximity Effects, the Superconducting Vortex Lattice Phase Diagram, and Supersolids

These researchers continued their investigations into three areas: proximity effects in heterostructures, particularly those involving superconductors and ferromagnets; phase diagram and density structure of superconducting vortex systems in the presence of pinning centers; and superfluid hydrodynamics and related phenomena in "supersolids.” In the first area, the group studies the behavior of high-quality multilayer and superlattice structures composed of superconducting and non-superconducting (including ferromagnetic) materials, using numerical methods they have developed to solve the exact microscopic equations for such systems. In the second area, the researchers study the phase diagram of type II superconductors in the vortex state, in the presence of both a magnetic field and pinning centers. They use numerical minimization of the appropriate free energy function (in terms of the time-averaged density variables) to find the free energy from which the phase diagram is obtained. The density structure at each minimum yields the correlation functions and the nature (crystal, glass, or liquid) of the phase. The third area, which is a new area of research beginning this period, studies the hydrodynamics of superfluids in confined geometries and its implication for "supersolid” phenomena.

Group Members

Paul Barsic, Arete Associates, Arlington, Virginia
Matthew Bruan, Undergraduate Student
Klaus Halterman, China Lake Research Center, China Lake, California
Igor Zutic, State University of New York, Buffalo, New York