Terahertz response of gadolinium gallium garnet (GGG) and gadolinium scandium gallium garnet (SGGG)

Abstract

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 nondispersive 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 Gd 3 + ions. A model of the material response tensor is determined, together with the Verdet and magneto-optic constants.