Wafer-level packaged RF-MEMS switches fabricated in a CMOS fab

Reports on wafer-level packaged RF-MEMS switches fabricated in a commercial CMOS fab. Switch fabrication is based on a metal surface micromachining process. A novel wafer-level packaging scheme is developed, whereby the switches are housed in on-chip sealed cavities using benzocyclobutene (BCB) as the bonding and sealing material. Measurements show that the influence of the wafer-level package on the RF performance can be made very small.\ud \u

Commensurate and Incommensurate Vortex States in Superconductors with Periodic Pinning Arrays

As a function of applied field, we find a rich variety of ordered and partially-ordered vortex lattice configurations in systems with square or triangular arrays of pinning sites. We present formulas that predict the matching fields at which commensurate vortex configurations occur and the vortex lattice orientation with respect to the pinning lattice. Our results are in excellent agreement with recent imaging experiments on square pinning arrays [K. Harada et al., Science 274, 1167 (1996)].Comment: 9 pages, 3 figures. Accepted to Physical Review

Revisiting Reader Privacy in the Age of the E-Book, 45 J. Marshall L. Rev. 175 (2011)

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London equation studies of thin-film superconductors with a triangular antidot lattice

We report on a study of vortex pinning in nanoscale antidot defect arrays in the context of the London Theory. Using a wire network model, we discretize the array with a fine mesh, thereby providing a detailed treatment of pinning phenomena. The use of a fine grid has enabled us to examine both circular and elongated defects, patterned in the form of a rhombus. The latter display pinning characteristics superior to circular defects constructed with the similar area. We calculate pinning potentials for defects containing zero and single quanta, and we obtain a pinning phase diagram for the second matching field, $H = 2 \Phi_{o}$.Comment: 10 pages and 14 figure

Individual and Multi Vortex Pinning in Systems with Periodic Pinning Arrays

We examine multi and individual vortex pinning in thin superconductors with periodic pinning arrays. For multi-vortex pinning we observe peaks in the critical current of equal magnitude at every matching field, while for individual vortex pinning we observe a sharp drop in the critical current after the first matching field in agreement with experiments. We examine the scaling of the critical current at commensurate and incommensurate fields for varied pinning strength and show that the depinning force at incommensurate fields decreases faster than at the commensurate fields.Comment: 4 figuure

Vortex phase diagram for mesoscopic superconducting disks

Solving numerically the 3D non linear Ginzburg-Landau (GL) equations, we study equilibrium and nonequilibrium phase transitions between different superconducting states of mesoscopic disks which are thinner than the coherence length and the penetration depth. We have found a smooth transition from a multi-vortex superconducting state to a giant vortex state with increasing both the disk thickness and the magnetic field. A vortex phase diagram is obtained which shows, as function of the magnetic field, a re-entrant behavior between the multi-vortex and the giant vortex state.Comment: 5 figures (post script files) include

Dynamic Phases of Vortices in Superconductors with Periodic Pinning

We present results from extensive simulations of driven vortex lattices interacting with periodic arrays of pinning sites. Changing an applied driving force produces a rich variety of novel dynamical plastic flow phases which are very distinct from those observed in systems with random pinning arrays. Signatures of the transition between these different dynamical phases include sudden jumps in the current-voltage curves as well as marked changes in the vortex trajectories and the vortex lattice order. Several dynamical phase diagrams are obtained as a function of commensurability, pinning strength, and spatial order of the pinning sites.Comment: 4 pages, 3 figures. To appear in Physical Review Letters. Movies available at http://www-personal.engin.umich.edu/~nor

Characterization of immune response to neurofilament light in experimental autoimmune encephalomyelitis

PMCID: PMC3856490This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.PMCID: PMC385649

Deformation and Depinning of Superconducting Vortices from Artificial Defects: A Ginzburg-Landau Study

Using Ginzburg-Landau theory, we have performed detailed studies of vortices in the presence of artificial defect arrays, for a thin film geometry. We show that when a vortex approaches the vicinity of a defect, an abrupt transition occurs in which the vortex core develops a ``string'' extending to the defect boundary, while simultaneously the supercurrents and associated magnetic flux spread out and engulf the defect. Current induced depinning of vortices is shown to be dominated by the core string distortion in typical experimental situations. Experimental consequences of this unusual depinning behavior are discussed.Comment: 10 pages,9 figure