Eur. Phys. J. B 7, 439-449 (1999)
https://doi.org/10.1007/s100510050632

Second-order phase transition induced by deterministic fluctuations in aperiodic eight-state Potts models

¹ Laboratoire de Physique des Matériaux (CNRS -UMR 7556) , Université Henri Poincaré, Nancy 1, 54506 Vandœuvre les Nancy Cedex, France
² Institut für Physik, Johannes Gutenberg-Universität Mainz Staudinger Weg 7, 55099 Mainz, Germany

Received: 18 March 1998
Revised: 29 June 1998
Accepted: 10 September 1998
Published online: 15 February 1999

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 , and are obtained at the new fixed point and crossover effects are discussed. Surface properties are also studied.