Die räumliche Magnetfeldverteilung und kritische Stromdichte in supraleitenden Blei-Wismut-Legierungen

Measurements of the spatial distribution of magnetic fields within superconductors were made with alloys of lead-bismuth, which allow for a large variation of superconducting properties. From these measurements critical current densities were derived as function of local magnetic field, and qualitative informations about surface currents are obtained. By Friedel et al. (1963) a field dependence of critial current density has been calculated, which makes a characteristic shape to be expected at low fields. This shape was found experimentally. A semiempirical extension of the relation given byKim et al. (1962) andAnderson (1962) is proposed, which satisfactory describes the measured current densities in the whole field range.