Second-Order Phase Transition Induced by Deterministic Fluctuations in Aperiodic Eight-State Potts Models

TL;DR

This study demonstrates that deterministic aperiodic fluctuations in the exchange interactions of an eight-state Potts model can induce a transition from a first-order to a second-order phase transition, altering critical behavior.

Contribution

It provides numerical evidence that aperiodic modulations can fundamentally change the nature of phase transitions in Potts models, revealing new fixed points and critical exponents.

Findings

Aperiodic fluctuations can induce second-order transitions in originally first-order systems.

Critical exponents are determined at the new fixed point.

Surface properties are also affected by aperiodic modulations.

Abstract

We investigate the influence of aperiodic modulations of the exchange interactions between nearest-neighbour rows on the phase transition of the two-dimensional eight-state Potts model. The systems are studied numerically through intensive Monte Carlo simulations using the Swendsen-Wang cluster algorithm for different aperiodic sequences. The transition point is located through duality relations, and the critical behaviour is investigated using FSS techniques at criticality. While the pure system exhibits a first-order transition, we show that the deterministic fluctuations resulting from the aperiodic coupling distribution are liable to modify drastically the physical properties in the neighbourhood of the transition point. For strong enough fluctuations of the sequence under consideration, a second-order phase transition is induced. The exponents $\beta/\nu$, $\gamma /\nu$ and $(1-\alpha)/\nu$ are obtained at the new fixed point and crossover effects are discussed. Surface properties are also studied.