Strong Faraday rotation in a topological insulator single layer using dielectric multilayered structures

Abstract

Topological insulators act as axionic materials in the presence of an external magnetic field or ferromagnetic dopants. We use a single topological insulator layer as a defect in a periodic multilayered structure to enhance the Faraday rotation. By adjusting the structure parameters, a Faraday rotation of 709 mrad is obtained at the defect mode. The transmission in wavelength with extreme values of Faraday rotation is higher than 95%. The high transmission and giant Faraday rotation result from the electromagnetic field localization at the topological insulator defect layer and strong interaction at the interfaces of the defect layer owing to the excitation of the defect mode. It was previously shown that multilayered structures consisting of eight alternating topological insulator layers demonstrated a Faraday rotation of 232 mrad with transmission of 94% [Phys. Rev. A 94, 033816 (2016)PLRAAN1050-294710.1103/PhysRevA.94.033816]. Therefore, the structure proposed here is an ideal system to observe strong Faraday rotation with high transmission in a single topological insulator layer. Furthermore, the effects of different parameters such as incident angle, thickness of the topological insulator defect layer, thickness of the dielectric layers, and number of unit cells on the Faraday rotation peak and its transmission are investigated.