Magneto-Optical Absorption in Dysprosium Iron Garnet in High Magnetic Fields

Optical absorption spectra in near infrared region were measured for dysprosium iron garnet (DyIG) in a temperature range from 3.8 K to above the compensation temperature θ c by using a superconducting magnet up to 150 kOe. Energy levels of the excited states 6 H 7/2 and 6 F 9/2 are calculated in the presence of the combined crystal and exchange fields. The peak positions corresponding to the transitions to these levels from the lowest split component of the ground state 6 H 15/2 are calculated and compared with the observed ones. By choosing the best fit value of the effective field, the agreement between theory and, experiment is fairly good as regards the overall features of spectrum.