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DY: Fachverband Dynamik und Statistische Physik
DY 13: Statistical Physics (general)
DY 13.7: Talk
Monday, March 7, 2016, 16:30–16:45, H48
Apparent non-universality due to competing anisotropies in 3D Zq models — •Thomas Lottermoser1, Andres Cano2, and Manfred Fiebig1 — 1Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland — 2CNRS, Université de Bordeaux, ICMCB, UPR 9048, 33600 Pessac, France
3D Zq models (q>4) like the q-state clock model, antiferromagnetic Potts model or the XY model with discrete q-fold anisotropy, are known to belong all to the XY-universality class at criticality, whereas the Zq anisotropy is dangerously irrelevant at TC. This leads to a new length scale associated to the fluctuations of the phase of the order parameter with a critical exponent νq>ν. Here ν is the standard XY critical exponent for the correlation length ξ of the order parameter amplitude. While there is a general agreement on this behavior in the literature, due to contradicting simulation results the question of the universality of νq aroused. We propose that these contradictions can be explained by the existence of competing anisotropies. Therefore, in our extensive Monte-Carlo study we investigated the critical behavior of a 12-state clock model with competing 6-fold anisotropy. As a result we found that the apparent non-universality of νq can indeed be traced back to the strength of the competing anisotropy we introduced in our model system. This allows us to continuously tune the value of νq between the universal values for the 6-state and 12-state clock models, respectively.