Nanoscale magnetization and third-order nonlinearity by the plasmon-induced inverse Faraday effect in graphene-covered semiconductors

Abstract

In this paper we study an approach for nanoscale spatially inhomogeneous excitation of quasistatic magnetic fields by the plasmon-induced inverse Faraday effect (IFE) in graphene-covered semiconductors and we present analytical and numerical results for the induced magnetic field distribution. The effective magnetic field is predicted to reach about 1 T and the direction of the magnetic field can be switched by surface plasmon polaritons propagating into the opposite direction. By electrically controlling the chemical potential of the graphene sheet the spatial inhomogeneity of the magnetization near field can be broadly tuned. The response of the induced magnetization to the plasmon propagation is manifested by a nonlinear phase shift which is measurable in the far field. By using the Lorentz reciprocity theorem we analytically calculated the nonlinear susceptibility and the nonlinear absorption coefficient in dependence on the chemical potential, the frequency, and the other material parameters. The plasmon-induced IFE and the nonlinearity can be very strong by decreasing the chemical potential which is flexibly controllable by using the graphene's gate voltage. The studied system could pave the way for an alternative approach for nanometer spatial all-optical magnetization control.