On the absence of a shift in the specific-heat transition of high temperature superconductors in a magnetic field

Abstract

The specific-heat transition in high temperature superconductors has been reported by several experimental groups to be independent of the magnetic field. This behavior is contrary to that of conventional superconductors. In this paper we demonstrate, on the basis of the Ginzburg-Landau theory, that this unique feature is a direct consequence of the very short coherence length, i.e. strong type II superconductivity alone. No additional assumptions regarding fluxoid properties are required. We also show that the typical specific-heat jumps are reduced by a factor of two in a finite field, with about four times the broadening of the transition width due to fluctuations. These results are in accord with the experiments.