The intermediate state of superconductors. I. Magnetization of superconducting cylinders in transverse magnetic fields

Abstract

The magnetization curves of tin and mercury cylinders were measured in transverse magnetic fields at a variety of temperatures in the superconducting range, and for various cylinder radii from 1.8 x 10 -2 to 1.7 X 10 -3 cm. As the cylinder radius was reduced the magnetization curve departed more and more from the simple form to be expected for an infinite cylinder of large radius, and the details of the departures agree qualitatively with the predictions of Landau’s theory of the intermediate state. The experiments show also that the sharp drop of magnetization corresponding to entry into the intermediate state coincides closely with the appearance of resistance. Detailed comparison with Landau’s theory (as worked out more fully by Andrew in part III) yields estimates of the surface energy at a boundary between normal and superconducting phases at the various temperatures.