Linear magnetooptic effect and visual observation of antiferromagnetic domains in an orthorhombic crystal of DyFeO3
Аннотация
We consider the linear magnetooptic effect in crystals of the orthorhombic magnetic space group. We find the form of the tensor qija describing the linear magnetooptic effect, and the corrections linear in H, ΔSεij to the components of the symmetric part of the dielectric permittivity tensor for the cases when the magnetic field is oriented along the two-fold axes. We have studied the linear magnetooptic effect experimentally in dysprosium orthoferrite at temperatures below the Morin temperature TM, with the magnetic field H and the light propagation direction along the c axis of the crystal (H‖k‖c). It is shown that in the antiferromagnet DyFeO3 for the case H‖c the linear magnetooptic effect leads to a rotation of the major axes of the dielectric tensor or the major axes of the optic indicatrix about the c axes by an angle linearly proportional to H. The field dependence of the rotation angle for the optical indicatrix and the off-diagonal symmetric components of the dielectric tensor sεxy are found. Using the linear magnetooptic effect we have visually observed and studied the antiferromagnetic domains. The field dependence of the Faraday effect is also obtained, and the off diagonal antisymmetric components axy are determined as a function of the magnetic field strength. It is shown that for DyFeO3 for H‖c and T < TM the components sεxy and aεxy causing the linear magnetooptic effect and the Faraday effect are of similar magnitude.