On the possible coexistence of spiral and collinear structures in antiferromagnetic KFe(MoO4)(2)

The static and resonance properties of a quasi-two-dimensional antiferromagnet phase on a distorted triangular lattice of KFe(MoO4)(2) have been experimentally studied. Magnetization curves exhibit features corresponding to the spin-flop transition in a collinear biaxial antiferromagnet and simultaneously show a magnetization plateau characteristic of a triangular spin structure. The magnetic resonance spectra also display absorption lines corresponding to the spin structures of both types. The experimental data are described in terms of a model comprising alternating weakly bound magnetic layers, in which the main two exchange integrals have different values. Below the Neel temperature (T-N = 2.5 K), some of these layers possess a collinear antiferromagnetic structure, while the other layers have a triangular or spiral structure. (C) 2004 MAIK "Nauka/Interperiodica"