Theory for optical activity in monolayer black phosphorus under external magnetic field

We derive an analytical model for calculating the optical activity in monolayer black phosphorus under an external magnetic field. By optimizing the parameters, the circular dichroism can be comparable to that in previously reported chiral metamaterials in a broad angle range. Besides, the optical activity including the circular dichroism, the circular conversion dichroism and the circular birefringence can be tuned almost linearly via changing the applied magnetic field magnitude. These results show that our proposed model would possess potential applications in polarization optics, stereochemistry, and molecular biology. Graphical abstract