Magneto-optical properties of the iron garnet Tb$_3$Fe$_5$O$_{12}$ near the magnetic compensation temperature

The magneto-optical susceptibility and magnetic hysteresis loops of the Faraday effect, which accompany the technical magnetization of the iron garnet Tb$_3$Fe$_5$O$_{12}$, have been investigated experimentally in the temperature region near the magnetic compensation point of this ferrimagnet $T_c$ = 249 K. It has been found that, during the technical magnetization as the temperature approaches the magnetic compensation point $T_c$, the velocity of domain walls increases, whereas the magneto-optical susceptibility has local maxima to the right and to the left from $T_c$. Mentioned features of magneto-optical properties of the iron garnet Tb$_3$Fe$_5$O$_{12}$ are associated with the resonance natural frequency of the domain wall oscillations in the crystal with the frequency of the alternating magnetic field. It has been shown that the used theoretical model of the magnetic resonance of domain walls makes it possible to consistently describe (at the qualitative level) the revealed regularities of the variation of the Faraday effect in the iron garnet Tb$_3$Fe$_5$O$_{12}$ near $T_c$.