SCALING ANALYSIS OF THE NEW MULTICRITICAL BEHAVIOR OF CSMNBR3 AND CSNICL3

Critical properties of the axial triangular antiferromagnet CsNiCl3 and the planar triangular antiferromagnet CsMnBr3 under an applied magnetic field are studied using scaling theory. Novel types of multicritical behavior observed in these compounds are associated with n=2 (CsMnBr3) and n=3 (CsNiCl3) chiral universality classes recently identified by the renormalization-group analysis. Various experimentally testable predictions are derived on the basis of a scaling ansatz combined with the numerical estimates of critical exponents. In particular, all phase boundaries emanating from the multicritical points are found to be scaled by the corresponding anisotropy-crossover exponent. It is also predicted that the criticality along the high-field critical line of CsNiCl3 (paramagnetic to spin flop) is of n=2 chiral universality. © 1990 The American Physical Society.