Low-temperature renormalization group study of uniformly frustrated models for type-II superconductors

TL;DR

This paper investigates phase transitions in frustrated SU(N) lattice models for type-II superconductors near the upper critical field using low-temperature renormalization group methods, revealing fixed points and critical behavior.

Contribution

It introduces a low-temperature RG approach to analyze phase boundaries and critical exponents in frustrated SU(N) models, extending understanding of superconducting phase transitions.

Findings

Phase boundary line corresponds to an ultraviolet-stable fixed point.

Critical exponents match those of non-frustrated systems.

Potential for continuous phase transition into the mixed state.

Abstract

We study phase transitions in uniformly frustrated SU(N)-symmetric $(2+\epsilon)$-dimensional lattice models describing type-II superconductors near the upper critical magnetic field $H_{c2}(T)$. The low-temperature renormalization-group approach is employed for calculating the beta-function $\beta(T,f)$ with $f$ an arbitrary rational magnetic frustration. The phase-boundary line $H_{c2}(T)$ is the ultraviolet-stable fixed point found from the equation $\beta(T,f)=0$, the corresponding critical exponents being identical to those of the non-frustrated continuum system. The critical properties of the SU(N)-symmetric complex Ginzburg-Landau (GL) model are then examined in $(4+\epsilon)$ dimensions. The possibility of a continuous phase transition into the mixed state in such a model is suggested.