Nonuniversality of ratios of critical and tricritical parameters in the three-state potts model with symmetry-breaking perturbations

Abstract

Fluctuation corrections to symmetry-breaking perturbations are shown to yield nonuniversal ratios for te lt, hc Ih, and Me IM, between the reduced temperature t, magnetic field h, and magnetization M of the underlying XY model at the criticai and tricritical points of the three-state Potts model. When applied to the trigonal-to-pseudotetragonal phase transition in uniaxially stressed SrTi03 along [1+8, 1+8, 1-28], 8«1, we finda non-negligible break to the universality of 8,18c, in distinction to previous work.