Inducing of the canted structure in tetragonal antiferromagnets with rhombic one-ion anisotropy by a longitudinal magnetic field

The case of a tetragonal antiferromagnet with magnetic point group 4/mmm is used to show that high magnetic one-ion rhombic anisotropy leads to vanishing of the sharp 'spin-flop' phase transition characteristic of uniaxial antiferromagnets. By making use of two linear magnetooptical effects (the Faraday effect and the linear magnetooptical effect), the authors found the dependence of the turn angle of the antiferromagnetic vector of the two-sublattice antiferromagnet CoF2 on the longitudinal magnetic field intensity which is in qualitative agreement with phenomenological analysis results. (orig.)