Accession Number : AD0703658

Title :   PATTERNS OF MAGNETIC FLUX PENETRATION IN SUPERCONDUCTING FILMS.

Descriptive Note : Technical rept.,

Corporate Author : HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS

Personal Author(s) : Goren,Robert N.

Report Date : JAN 1970

Pagination or Media Count : 204

Abstract : 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)

Descriptors :   (*SUPERCONDUCTORS, MAGNETIC FIELDS), (*MAGNETIC FIELDS, PENETRATION), METAL FILMS, HALL EFFECT, INDIUM, LEAD(METAL), TIN

Subject Categories : Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE