Intermediate State of Superconductors: Influence of Crystal Structure

Abstract

The structure of the intermediate state has been studied in tin single crystals. In the purest crystals, an anisotropy is observed which is caused by the anisotropic resistance of the normal phase. The anisotropy of the structure changes sign as the temperature is lowered because of the very large magnetoresistance of pure tin. Superconducting-normal boundary (surface) energy values for tin single crystals have been measured and agree with those found earlier for polycrystalline tin samples. Boundary energy values for thallium have also been measured and agree with theoretical predictions.