Functional renormalization group approach to non-collinear magnets

TL;DR

This paper uses a functional renormalization group method with various truncations to analyze non-collinear magnets, concluding no stable fixed point exists for the physically relevant cases of N=2,3 in three dimensions, challenging some previous theories.

Contribution

It introduces a functional renormalization group framework with multiple truncations to study the critical behavior of non-collinear magnets across dimensions.

Findings

No stable fixed point for N=2,3 in d=3, indicating a first-order transition.

Results align with epsilon-expansion and contradict some conformal bootstrap predictions.

Method provides a new perspective on the critical properties of non-collinear magnetic systems.

Abstract

A functional renormalization group approach to $d$-dimensional, $N$-component, non-collinear magnets is performed using various truncations of the effective action relevant to study their long distance behavior. With help of these truncations we study the existence of a stable fixed point for dimensions between $d= 2.8$ and $d=4$ for various values of $N$ focusing on the critical value $N_c(d)$ that, for a given dimension $d$, separates a first order region for $N<N_c(d)$ from a second order region for $N>N_c(d)$. Our approach concludes to the absence of stable fixed point in the physical - $N=2,3$ and $d=3$ - cases, in agreement with $\epsilon=4-d$-expansion and in contradiction with previous perturbative approaches performed at fixed dimension and with recent approaches based on conformal bootstrap program.