Patterns of Magnetic Flux Penetration in Superconducting Films

Download or read book Patterns of Magnetic Flux Penetration in Superconducting Films written by Robert N. Goren and published by . This book was released on 1970 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Patterns of magnetic flux penetration have been observed in thin superconducting films of tin, lead, and indium in perpendicular applied fields of 0.1 - 100 Oe. The flux patterns were studied by measuring the magnetic field very close to the film with a high resolution Hall probe which could be scanned in a plane parallel to the surface of the film. The observed patterns appear to contain both laminar and round normal regions. Using Landau's theory of the intermediate state as a guide, a similar model is considered in which the flux pattern consists of normal spots, rather than laminae. Within the accuracy of an approximate calculation, the free energy of both models is roughly the same in low fields, which implies that both spots and laminae can exist in the intermediate state. The results for the thicker indium samples (1.1 - 6.3 micrometers) are in good agreement with the temperature, field, and thickness dependences of either Landau's laminar model or our spot model for the intermediate state. (Author).