Magnetic field tunable circular dichroism based on MnF 2 chiral metasurfaces

Abstract This study proposes an antiferromagnetic MnF 2 chiral metasurface (MS) exhibiting significant magneto-tunable circular dichroism (CD) properties. The MS is composed of five periodically arranged rectangular holes within an MnF 2 layer, enabling effective characterization of both its CD of reflection ( CD R ) and transmission ( CD T ). The CD of the MS can be adjusted by an external magnetostatic field ( H 0 ). We found that within a frequency range spanning from 0.273 THz to 0.31 THz, the CD R values can markedly shift from 0 to −0.605, while the CD T values oscillate between −0.65 and 0.757. Utilizing multipole decomposition, we reveal that the origin of both CD R and CD T lies in the electric quadrupole (EQ) and magnetic dipole (MD) moments. The research concurrently investigates the MS’s tolerance to incident angle and structural fabrication variations, demonstrating its robustness. This MnF 2 MS not only demonstrates potential as a high-performance optical modulator but also offers valuable insights for the development of next-generation integrated photonic technologies.