Interaction of Vortices in Type-II Superconductors nearT=Tc

Abstract

The theory of Müller-Hartmann and Kramer for the interaction of widely separated vortices is extended to temperatures immediately below $T_c$. The interaction is found to be attractive below $T_c$ for type-II materials with $k\approx \frac{1}{\sqrt{2}}$ and not too small a mean free path, in agreement with experimental observations on such materials. The phenomenon of field reversal and the work of Eilenberger and Büttner are shown to be unrelated to an attractive interaction between vortices and the consequent first-order transition at the lower critical field, at least for temperatures near $T_c$; it is shown how field reversal, if it occurs in the mixed state, might result in an attractive interaction at lower temperatures.