Studies of magnetogyration in cubic Bi12GeO20 crystals using small-angular magnetooptic polarimetry

We present the results of studies for magnetogyration (MG) effect in non-centro-symmetric, non-polar Bi12GeO20 crystals performed with the small-angular polarimetric mapping technique. The magnitude of MG rotation obtained with the small-angular mapping is close to the corresponding values obtained recently on the basis of single-ray polarimetry. Our results demonstrate that multiple reflections of light play a key role in the studies of MG effect in Bi12GeO20 crystals. They lead to the error, which is at least two times as large as the expected value of the MG rotation.