We point out interesting effects of additional massless Dirac fermions with $N_{\mathrm{F}}$ colors upon the critical behavior of the Ginzburg-Landau model. For increasing $N_{\mathrm{F}},$ the model is driven into the type-II regime of superconductivity. The critical exponents are given as a function of $N_{\mathrm{F}}.$

• Received 25 January 2002

DOI:https://doi.org/10.1103/PhysRevB.66.012504