The anisotropic magnetic property and Faraday rotation in Er3Ga5O12 under high magnetic field

A theoretical investigation on the anisotropic magnetic property and Faraday rotation in Er3Ga5O12 (ErGaG) is presented. With particular consideration of the anisotropy of the exchange interaction between rare-earth ions (Er3+), the magnetization, based on the quantum theory, in ErGaG under high magnetic field (HMF) is calculated. Theoretical calculations show that the appropriate choice of the crystal field (CF) parameters is of great importance. A novel three-level model is presented, and in terms of this model the Faraday rotation under HMF is calculated. In addition, it is demonstrated that the Faraday rotation (θ) depends not only on the magnetization (M) but also on the magnetic field (He). The theory is in good agreement with the experiment.