QUASI-ONE-DIMENSIONAL TRIANGULAR ANTIFERROMAGNETS

ABX3-type antiferromagnets on a stacked triangular lattice usually possess two essential peculiarities: 1) Substantial quasi-one-dimensionality, J/J' approximately 10-10(3). 2) Noncollinear 120-degrees magnetic ordering at T < T(N) is similar to (JJ')1/2. We investigated the spin-reorientation process and ESR spectra in a wide frequency-field interval for two types of such compounds: easy-axis (CsNiCl3, RbNiCl3) and easy-plane (CsMnBr3, RbMnBr3). ESR absorption spectra measured experimentally at various temperatures were mainly in good agreement with those calculated theoretically. The values of parameters derived from our measurements and their temperature dependencies coincide well with the results of other investigations.