Terahertz Response Of Gadolinium Gallium Garnet (Ggg) And Gadolinium Scandium Gallium Garnet (Sggg)

We report the magneto-optical response of gadolinium gallium garnet (GGG) and gadolinium scandium gallium garnet (SGGG) at frequencies ranging from 300 GHz to 1 THz and determine the material response tensor. Within this frequency window, the materials exhibit non-dispersive and low-loss optical responses. At low temperatures, significant terahertz Faraday rotations are found in the (S)GGG samples. Such a strong gyroelectric response is likely associated with the high-spin paramagnetic state of the Gd3+ ions. A model of the material response tensor is determined, together with the Verdet and magneto-optic constants.