No abstract

Spectroscopic and magnetooptical investigations of spin-reorientation transition induced by a magnetic field in antiferromagnetic terbium ferroborate TbFe3(BO3)4 were performed. In the phase-transition region, a magnetic intermediate state with a periodic alternation of domains of initial and spin-flopped magnetic phases appears. As a result, a strong light scattering by the crystal takes place. It is shown that the main mechanism of light scattering is related to an appearance of the large Faraday rotation in a high-field magnetic phase. Visual polarization investigations of the domain structure in the intermediate state were carried out. The energy of the interphase boundary between the antiferromagnetic and high-field magnetic phases was calculated. The existence domain of the intermediate magnetic state was determined in the H–T coordinates.

Light-induced change in the optical absorption of the garnet Ca3Mn2Ge3O12 has been found. The magnitude of the light-induced optical absorption does not depend on the polarization state of the exciting illumination. The effect persists for a long time at low temperatures and can be attributed to light-induced generation or redistribution of Mn4+ ions in the crystal.