Critical behavior of the spin correlation function in Ashkin-Teller and Baxter models with a line defect

TL;DR

This paper investigates the critical spin correlation functions in Ashkin-Teller and Baxter models, demonstrating they decay with the same critical exponent as the Ising model, even with line defects present.

Contribution

It extends continuum fermion field techniques to analyze the effect of line defects on critical exponents in these models.

Findings

Correlation decays with Ising-like critical exponent.

Line defects do not alter the critical index of magnetic correlations.

Method applies to models with line defects, preserving critical behavior.

Abstract

We consider the critical spin-spin correlation function of the Ashkin-Teller and Baxter models. By using path-integral techniques in the continuum description of these models in terms of fermion fields, we show that the correlation decays with distance with the same critical exponent as the Ising model. The procedure is straightforwardly extended to take into account the presence of a line defect. Thus we find that in these altered models the critical index of the magnetic correlation on the defect coincides with the one of the defective 2D Ising or Bariev's model.