LOW-TEMPERATURE RENORMALIZATION-GROUP STUDY OF UNIFORMLY FRUSTRATED MODELS FOR TYPE-II SUPERCONDUCTORS

We study phase transitions in uniformly frustrated SU(N)-symmetric (2 + epsilon)-dimensional lattice models describing type-II superconducto rs near the upper critical magnetic field H-c2(T). The low-temperature renormalization-group approach is employed for calculating the beta f unction beta(T,f) with f an arbitrary rational magnetic frustration. T he phase-boundary line H-c2(T) is the ultraviolet-stable fixed point f ound from the equation beta(T,f)=0, the corresponding critical exponen ts being identical to those of the nonfrustrated continuum system. The critical properties of the SU(N)-symmetric complex Ginzburg-Landau mo del are then examined in (4 + epsilon) dimensions. The possibility of a continuous phase transition into the mixed state in such a model is suggested. [S0163-1829(98)00441-X].