Effect of weak disorder in the Fully Frustrated XY model

TL;DR

This study investigates how weak positional disorder affects the critical behavior of the Fully Frustrated XY model, revealing significant changes in critical exponents and helicity modulus even at small disorder levels.

Contribution

It provides the first detailed Monte Carlo analysis of weak disorder effects on the Fully Frustrated XY model's critical properties.

Findings

Critical exponent for chiral correlation length is approximately 1.7 at small disorder.

Helicity modulus jump exceeds the universal XY model value.

Weak disorder significantly alters critical behavior.

Abstract

The critical behaviour of the Fully Frustrated XY model in presence of weak positional disorder is studied in a square lattice by Monte Carlo methods. The critical exponent associated to the divergence of the chiral correlation length is found to be equal to 1.7 already at very small values of disorder. Furthermore the helicity modulus jump is found larger than the universal value expected in the XY model.