Magnetic circular dichroism and the optical detection of magnetic resonance for the Bi antisite defect in Bi₁₂GeO₂₀

Abstract

We report on the optical detection of electron paramagnetic resonance at 36 GHz, 67 GHz and 70 GHz for all the absorption bands of Bi12GeO20 (BGO) in the visible spectral range. This completes our previous studies and demonstrates clearly that the three major magnetic circular dichroism features do belong to the same isotropic centre, i.e., a Bi3+Ge+h defect with the hole being delocalized onto the four surrounding oxygen atoms. We provide a simple explanation for the unusual sign of ODMR and the transient behaviour of the magnetic circular dichroism at resonance.