Temperature behavior of magneto-optical activity of $f$-$f$ transitions in $\mathrm{Dy}^{3+}$ ion in oxide glasses

Temperature dependencies of absorption and magnetic circular dichroism (MCD) spectra of $f$-$f$ transitions $^6\mathrm{H_{15/2}\to{}^6F_{3/2}}$, $^6\mathrm F_{5/2}$, $^6\mathrm{(F_{7/2}+H_{5/2})}$, $^6\mathrm{(F_{9/2}+H_{7/2})}$ in $\mathrm{Dy}^{3+}$ ions in glasses: $\mathrm{Dy_2O_3-P_2O_5-SiO_2-GeO_2}$ and $\mathrm{Dy_2O_3-La_2O_3-Al_2O_3-B_2O_3-SiO_2-GeO_2}$ with different concentrations of $\mathrm{Dy}^{3+}$ ions have been studied in temperature range 94–293 K. Basing on this data, absolute values and temperature dependences of the paramagnetic magneto-optical activity (MOA) of the transitions have been determined. It has been found out that temperature dependences of MOA of some transitions strongly differ from the Curie–Weiss law. The origin of the different value and different temperature behavior of MOA of identical transitions in the different glasses was analyzed and it has been showed that this is a consequence of different symmetry of the nearest environment of $\mathrm{Dy}^{3+}$ ions in the studied oxide glasses. It has been also shown that MOA contains contributions of different value and sign. Correlation of them depends on type of the transition and on the symmetry of the environment. It leads to anomalous temperature behavior of the paramagnetic magneto-optical activity.