The Local Potential Approach to frustrated antiferromagnets

TL;DR

This paper uses a nonperturbative renormalization group approach within the local potential approximation to analyze the critical behavior of classical frustrated antiferromagnets, providing detailed numerical analysis of fixed points across dimensions.

Contribution

It introduces a numerical method to solve NPRG equations for frustrated systems, clarifies the phase transition boundaries, and compares results with other theoretical approaches.

Findings

Computed the function N_c(d) for d between 4 and 2.2.

Confirmed previous NPRG results with improved numerical methods.

Contradicted fixed dimension perturbative and conformal bootstrap results.

Abstract

We revisit the critical behavior of classical frustrated systems using the nonperturbative renormalization group (NPRG) equation. Our study is performed within the local potential approximation of this equation to which is added the flow of the field renormalization. Our flow equations are functional to avoid possible artifacts coming from field expansions which consists in keeping only a limited number of coupling constants. We present a simple numerical method to follow the fixed point solution of our equations by changing gradually the dimension d and the number N of spin-components. We explain in details the advantage of this method as well as the numerical difficulties we encounter, which become severe close to d = 2. The function N_c(d) separating the regions of first and second order in the (d,N) plane is computed for d between 4 and 2.2. Our results confirm what was previously found within cruder approximation of the NPRG equation and contradict both the fixed dimension perturbative approach and the results obtained within the conformal bootstrap approach.