Odd magnetic dichroism of linearly polarized light in the antiferromagnet MnF2

Abstract

The two-sublattice tetragonal antiferromagnetic crystal manganese fluoride is found to exhibit dichroism induced by a magnetic field H∥C4∥Z for linearly polarized light propagating along the tetragonal axis of the crystal also. The observed effect is odd with respect to the sign of the z projection of the field and the operation of reversing the directions of the sublattice magnetic moments of the antiferromagnet. The effect can be used for optical visualization of 180-degree (time-reversed) antiferromagnetic domains in MnF2.

Control of antiferromagnetic domain distribution via polarization-dependent optical annealing

“…The third term describes the nonlocal interactions of the order parameter, and c is a parameter describing this non-locality. The last term includes the effective staggered field, H eff , mainly via magneto-elastic effects 10 11 41 and higher-order magnetic susceptibilities 12 . Previous studies of choosing an antiferromagnetic state over a whole crystal of MnF 2 were achieved by controlling this last term.…”

“…This method to control antiferromagnetic order was employed by Kharchenko et al . 12 , and we employed the same technique.…”

“…For example, the linear magnetoelectric effect can couple electric field and antiferromagnetic order parameters, but its symmetrical requirement restricts its applications to particular materials 3 . Other than the linear magnetoelectric effect, control of the antiferromagnetic domains has been limited to methods employing indirect parameters, such as stress 10 11 and magnetic field via higher-order magnetic susceptibilities 12 . Selection of an antiferromagnetic state over a whole crystal has been achieved by these methods, but the difficulty of local control of these macroscopic parameters has hindered spatial control of antiferromagnetic domain structures, and an external stimulus with a better control for local manipulation has been awaited.…”

Metallic antiferromagnets

“…Quadratic magneto-optical effects include magnetic linear dichroism 190,191 and magnetic linear birefringence of reflected 166,192 (also called quadratic MOKE or Hubert-Schäfer effect) or transmitted light 163 (also called Voigt effect or Cotton-Mouton effect). Magnetic linear birefringence arises from a contribution to the dielectric tensor that is separate from crystal-structure driven terms.…”

“…190 Kharchenko et al report observation of magnetic linear dichroism in MnF 2 with the magnitude of the effect being large enough to visually observe antiferromagnetic domains in the material. 191 While both of these materials are non-metallic, the potential of linear magnetic dichroism for visualizing antiferromagnetic domains renders this effect of interest also for metallic antiferromagnets.…”