Applied Electromagnetics Using QuickField and MATLAB

Section 8.4 - Superconductivity: Type-I and Type-II Superconductors

A key quantity that distinguishes different types of superconductors is the Ginzburg-Landau parameter

where the coherence length is a measure of transition distance between superconducting and normal regions and λ is the London penetration depth. Superconductors with smaller values of are referred to as Type-I and are characterized by a positive surface energy. Type-I superconductors tend to minimize the normal-superconductor interfacial area if both normal and superconducting regions exist in the sample. Type-II superconductors, on the other hand, have values of with a negative surface energy and a maximization of the normal-superconductor interface area. The Ginzburg-Landau theory gives the lower critical field of a Type-II superconductor below which no flux will penetrate the superconductor

The upper critical field of a Type-II superconductor is given by

If a transport supercurrent also flows in addition to the vortex current, there will be a Lorentz force acting on the vortices, where points in the direction of flux penetration into the superconductor.

QuickField calculations of superconductors in external fields will be handled with the application of boundary conditions and material properties discussed in the following sections.

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Category: Superconductors and Superconducting Materials
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