Surface Enhancement of Superconductivity in Tin

The possibility of surface enhancement of superconductivity is examined experimentally. It is shown that single crystal tin samples with cold-worked surfaces represent a superconductor with a surface-enhanced order parameter (or negative surface extrapolation length b), whose magnitude can be controlled.Comment: 8 pages, 4 figure

Brewery Utilities (Manual of Good Practice)

The European Brewery Convention commissioned a group representing brewery engineers with an academic advisor to produce this manual. It covers the supply and efficient utilisation of water, fuel and electricity in breweries

Brewery Utilities (Manual of Good Practice)

The European Brewery Convention commissioned a group representing brewery engineers with an academic advisor to produce this manual. It covers the supply and efficient utilisation of water, fuel and electricity in breweries

Vortex pinning in superconducting Nb thin films deposited on nanoporous alumina templates

We present a study of magnetization and transport properties of superconducting Nb thin films deposited on nanoporous aluminium oxide templates. Periodic oscillations in the critical temperature vs. field, matching effects in fields up to 700 mT and strongly enhanced critical currents were observed. These fields are considerably higher than those typical for periodic pinning arrays made by lithographic techniques, which reflects the benefits of nanostructuring superconductors by using self-organized growth. This method provides a periodic pinning potential with sub-100 nm spacing between the pinning centers, which enhances vortex pinning in broad field and temperature ranges. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 200674.25.Qt Vortex lattices, flux pinning, flux creep, 74.78.Na Mesoscopic and nanoscale systems,

High field matching effects in superconducting Nb porous arrays catalyzed from anodic alumina templates

Vortex pinning in a superconducting Nb thin film deposited on an anodically grown alumina template is investigated. Anodic oxidation of aluminium layers permits under specific conditions the formation of highly ordered porous alumina, a membrane-like structure consisting of triangular arrays of parallel pores. Its pore diameter and interpore distance are set by careful tuning of the anodization parameters. A superconducting Nb thin film is deposited directly onto the alumina film. The porous alumina acts as a template and it allows Nb to form a periodic pinning array during its growth. Pinning force vs. field measurements derived from magnetization measurements, show matching effects in fields up to 1 T. We demonstrate that the anodic alumina template with 50 nm interpore spacing provides enhanced vortex pinning in a large field and temperature range. (C) 2007 Elsevier B.V. All rights reserved

Vortex pinning in superconductors laterally modulated by nanoscale self-assembled arrays

Being the exponent of the so-called "bottom-up" approach, self-assembled structures are now-a-days attracting a lot of attention in the fields of science and technology. In this work, we show that nanoscale self-assembled arrays used as templates can provide periodic modulation in superconducting thin films by studying their vortex pinning properties. In this work advantage was made of the fact that self-organized assemblies of identical units such as colloidal crystals and anodic aluminum oxide provide extended periodic topographic surfaces. By directly growing Nb on top of these self-assembled arrays, the templating effect was exploited in order to achieve triangular and honeycomb arrays of pinning centers in thin superconducting films. We show experimentally that periodic matching is achieved in both systems at magnetic fields, well above those present in lithographically prepared pinning arrays (up to 1 T!). Furthermore, we demonstrate in the case of anodic aluminum oxide that the presence of porous antidots in Nb not only provides strongly increased critical currents but also conserves matching at temperatures well below the critical temperature. The studies conducted on these systems indicate that the method of template growth might be considered as a viable alternative for the incorporation of periodic pinning arrays in superconducting applications of today and the future. (c) 2008 Elsevier B.V. All rights reserved

Porous Silicon Templates for Superconducting Devices

The use of porous silicon (PS) templates in the field of superconducting nanoelectronics is reviewed. We focus on the influence of the morphology of the pores (porosity, average pore diameter) on the superconducting properties of ultrathin films deposited on these templates. We describe and discuss some basic and advanced properties of the obtained nanostructured superconductors. In particular, we show that, due to the extremely reduced dimensions of PS templates, the formation of commensurate vortex structures can be realized at low temperatures and at matching fields as high as μ0H1 1 T. We also show that with this fabrication procedure, we can obtain networks of one-dimensional superconducting nanowires, which exhibit features typical of quantum phase slip (QPS) phenomena. This creates preconditions for the development and implementation of new highly sensitive radiation detectors, magnetometers, QPS qubits, QPS transistors, and quantum current standards

Porous silicon templates for superconducting devices

The use of porous silicon (PS) templates in the field of superconducting nanoelectronics is reviewed.We focus on the influence of the morphology of the pores (porosity, average pore diameter) on the superconducting properties of ultrathin films deposited on these templates. We describe and discuss some basic and advanced properties of the obtained nanostructured superconductors. In particular, we show that, due to the extremely reduced dimensions of PS templates, the formation of commensurate vortex structures can be realized at low temperatures and at matching fields as high as μ0H1≈ 1 T. We also show that with this fabrication procedure, we can obtain networks of one-dimensional superconducting nanowires, which exhibit features typical of quantum phase slip (QPS) phenomena. This creates preconditions for the development and implementation of new highly sensitive radiation detectors, magnetometers, QPS qubits, QPS transistors, and quantum current standards