Microwave and magneto-optic properties of ε-Fe2O3 nanoparticles arising in borate glasses doped with Fe and Gd

The e-Fe 2 O 3 nanoparticles in borate glasses co-doped with low concentrations of Fe 2 O 3 and Gd 2 O 3 were investigated with two experimental techniques – visible magnetic circular dichroism (MCD) and electron spin resonance (ESR). The most prominent features of the MCD spectra are: non-linear dependence of the spectral maxima intensities on the Gd concentration and strong increase with the temperature decrease. The ESR spectra of these glasses exhibit two features with g = 4.3 due to the diluted Fe 3+ ions and 2.0 associated both with Fe 3+ ions and with nanoparticles. The integrated spectra intensities do not follow the T -1 Curie law suggesting a considerable contribution from the magnetically ordered nanoparticles to ESR. Analysis of the MCD and ESR concentration dependences allow suggestion on the Gd ions incorporation into nanoparticles.