Crossover near fluctuation-induced first-order phase transitions in superconductors

Abstract

Crossover near the fluctuation-induced first-order transition in superconductors is studied to first order in $\ensuremath{\epsilon}=4\ensuremath{-}d$. We find that the effective exponent ${\ensuremath{\gamma}}_{\mathrm{eff}}$ for the susceptibility of type-II systems falls from its value for the chargeless system to the mean-field value unity well before the first-order transition occurs. Although such effects are probably unobservable in real superconductors, these calculations may have some relevance to the nematic to smectic-$A$ transition in liquid crystals.