Light scattering in FeCl2 at the metamagnetic transition

Light scattering by coexisting magnetic phases, that is domain structure, has been observed previously in various ferro‐ and ferrimagnetic crystals, CrBr3, EuO, MnBi and Y3Fe5O12 and in the antiferromagnets FeCl2 and Dy3Al5O12. Recently Griffin1 et al. reported that in FeCl2 at the metamagnetic transition the scattering differed for the two senses of circular polarization. They used this apparent ’’magnetic circular dichroism’’ to determine features of the magnetic phase diagram. Though an explanation was offered, the origin of this polarization asymmetry has remained a vexing puzzle. We have studied light scattering in (0001) sublimation sheets (20‐100μm thick) of FeCl2 with [0001] parallel to both the applied field and the direction of propagation of light. Asymmetry in the scattering of two circular polarizations was encountered throughout the spectral range 0.4−1.1 μm and the temperature range 2.1−20.0K. The diffraction and its dependence on circular polarization are explained in terms of the refracti...