Lowering of the optical class of an antiferromagnetic crystal, induced by a longitudinal magnetic field
Kharchenko N.F., Eremenko V.V., Belyi L.I.
It was observed in experiment that a longitudinal magnetic field induces birefringence, linear in the field intensity, in a two-sublattice collinear tetragonal antiferromagnet in which linearly polarized light propagates along the tetragonal axis. The magnitude of the birefringence makes it possible to distinguish visually, in a magnetic field, antiferromagnetic states that have different directions of the antiferromagnetic vector. It is shown that the distortions in the tetragonal-structure field are not the decisive factor in the observed magneto-optical effect.