Critical properties of helical magnets and triangular antiferromagnets

Abstract

The critical behavior of certain frustrated magnetic crystals with competing interactions has been studied. It is predicted that the layered-triangular lattice antiferromagnets VCl2, VBr2, CsMnBr3, and CsVCl3 and the helical magnets β-MnO2, MnAu2, Ho, Dy, and Tb should belong to new universality classes characterized by novel critical exponents: α≂0.34–40, β≂0.25–0.28, γ≂1.1, and υ≂0.53–0.55. The chirality κ is a new relevant operator in these systems; the corresponding exponents are found to be βκ ≂0.40 and γκ ≂0.80, which satisfy the Essam–Fisher relation with ακ ≡α. The possibility of observing the chiral order is mentioned.