Directional dichroism at the spin-wave excitations of multiferroic Ni3TeO6

In physical systems simultaneously breaking time-reversal and spatial inversion symmetries the strength of absorption for two counter-propagating light beams can be different, which phenomenon is termed as non-reciprocal directional dichroism. Until recent experiments on multiferroic materials this effect was generally found to be weak. The multiferroic Ni3TeO6 shows strong directional dichroism in its spin excitations even for unpolarized light. The temperature- and magnetic field dependence of these exotic resonances was followed up to the Néel temperature and up to 30 T magnetic field, respectively.