THE OPTICAL-PROPERTIES OF ANTIFERROMAGNETIC CHROMIUM-OXIDE IN TRANSMISSION

A multipole theory of wave propagation in a magnetic medium is applied to a single-domain crystal of Cr2O3 in the electric quadrupole-magnet ic dipole approximation. It is shown that the optical response of the crystal may be regarded as the net effect of three independent linear birefringences and their respective dichroisms, of which two are non-r eciprocal and change sign when either the light path or spins are reve rsed; the third is reciprocal and insensitive to these influences. The six properties are contained in the Jones M-matrix, which describes t he effect of an arbitrary length of the crystal on an incident polariz ed light beam. This matrix is used to express transmitted intensities, for different incident and analysed polarization states, in terms of crystal properties. An experiment is suggested for determining the six optical properties of Cr2O3 from suitable measurements of the transmi tted intensities.