Room Temperature Terahertz Magneto-optical Effect of Wafer-scale TbCaBi:Rare-earth Iron Garnet Single-crystal Film under Low Magnetic Field Intensity

A large-area single-crystal thick film of RIG was successfully created on a 3-inch GGG substrate using the liquid phase epitaxy technique. The RIG crystal had a thickness of approximately 390 micrometres. In the frequency range of 0.1 to 1.0 THz, the RIG material exhibited a notable refractive index of approximately 4.40, with a transmission rate of approximately 40% and an absorption rate varying between 6 and 50 cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup>. Moreover, an investigation into the MO characteristics of the RIG material at THz frequencies was conducted utilising THz time-domain spectroscopy. The experimental results provided evidence of the presence and significance of the MO effect in the RIG crystal. To gain further insight, the THz Faraday rotation angle of RIG crystal was measured under the influence of an external magnetic field of 0.18 T using a THz-TDS system. It is noteworthy that the recorded Faraday rotation angle reached 17°, with the calculated Verdet constant for the RIG sample estimated to be approximately 140°/mm/T. These results highlight the distinctive characteristics of the large-area single-crystal thick film of RIG, which exhibits minimal losses, exceptional transmission capabilities, and robust MO effects within the THz spectral domain. Consequently, this material displays considerable potential for a diverse range of applications, including THz magnetic polarization.