The nonlinear and reciprocal properties of magneto-optical (MO) effects in paramagnetic media under a high magnetic field are investigated by theoretical calculations. It is indicated that the Faraday effect in paramagnetic MO media has the obvious nonlinearity and reciprocity when the thermal energy $k_{B}T$ approaches the effective field energy ${\mu }_0{\mu }_B{H}_i$ $\left({\mu }_0{\mu }_B{H}_e\right)$. In addition, the MO effects, especially under an extremely high magnetic field, are found to depend essentially on the effective field $H_i$ except the magnetization $M$. Our results are shown to be consistent with the experimental data while they are dramatically contrary to the current widely-accepted conclusions of classical MO theories.

• Received 11 November 2004

DOI:https://doi.org/10.1103/PhysRevB.72.014415