Gate tunable magneto-optical effects in layered antiferromagnets

It has long been believed that the Faraday and the magneto-optic Kerr effects are absent in collinear antiferromagnets due to their vanishing net magnetic moment. To the contrary, using first-principles calculations we demonstrate that these effects can be controlled by a perpendicular voltage in bilayer MnPSe$_3$, which has a collinear AF-N{\'e}el spin texture. The Kerr rotation can be as high as 10 mrad, and is reversed on the reversal of the polarity of gate voltage. The tunable nature of the magneto-optic effects can result in novel optoelectronic device applications. It also provides a nondestructive way to characterize the magnetic ground state of 2D materials.