Low Energy Excitations and Phase Transitions in the Frustrated Two-Dimensional XY Model

TL;DR

This study investigates phase transitions and low energy excitations in the 2D XY model under magnetic fields, revealing that disorder influences critical behavior and domain walls play a key role.

Contribution

It demonstrates that the critical exponents in the disordered 2D XY model match those of the 2D Ising model, highlighting the role of domain walls in phase transitions.

Findings

Critical exponents align with the 2D Ising model for certain parameters.

Disorder affects the nature of phase transitions.

Domain walls are the main low energy excitations.

Abstract

We study the critical properties of the two-dimensional (2D) XY model in a transverse magnetic field with filling factors f=1/3 and 2/5. To obtain a comparison with recent experiments, we investigate the effect of weak quenched bond disorder for f=2/5. A finite-size scaling analysis of extensive Monte Carlo simulations strongly suggests that the critical exponents of the phase transition for f=1/3 and for f=2/5 with disorder are those of the pure 2D Ising model. The relevant low energy excitations are domain walls, and we show that their properties determine the nature of the phase transition.