Terahertz Faraday rotation of aluminum-substituted barium hexaferrite

Faraday rotation effect of magnetized hexagonal ferrites BaAlxFe12−xO19 ( x = 1.4 , 2.0) with a varied density in the frequency range of 0.1–1.0 THz was investigated using terahertz (THz) time-domain spectroscopy. Broadband polarization rotation up to 20° for 1-mm thick hexaferrite was demonstrated at room temperature. It was shown that the value of Faraday rotation can be effectively controlled by varying hexaferrite sample density as well as Al concentration. From the experimental data, the full permittivity tensor characterization of different hexaferrite samples was extracted to double-check the calculation of Faraday rotation. The obtained results demonstrate prospects for the utilization of BaAl1.4Fe10.6O19 hexaferrite with the highest density as a broadband self-biased complete THz isolator with moderate insertion losses below 5 cm–1 in the range up to 0.4 THz.