Symmetry aspects of electric-field induced breaking of chiral degeneracy in the stacked triangular antiferromagnet

Abstract

Abstract A pedagogical exposition is given of our earlier work [Phys. Rev. B, 43, 13786 (1991)] on chirality selection by magnetoelectric coupling in frustrated hexagonal antiferromagnets. Symmetry arguments are developed which demonstrate that an applied electric field introduces a term in the Hamiltonian of the Dzyaloshinskii-Moriya type which selects a right or left-handed helicity of the 120° basal-plane spin structure. These results are of particular interest in view of recent predictions from Monte Carlo simulations and renormalization group calculations. It is argued that good candidates for the experimental realization of such effects are the hexagonal insulators of the type CsMnBr3. 75.10.Hk, 75.30.Kz, 75.80. + q.