Inverse Faraday effect from the orbital angular momentum of light

Abstract

It is usually admitted that the inverse Faraday effect (IFE) originates from the spin angular momentum (SAM) of light. In this paper, we show that part of the IFE in a metal is induced by the orbital angular momentum (OAM) of light. On the basis of a hydrodynamic model of the conduction electron gas, we describe the dependence of the IFE on the spin and orbital angular momenta as well as spin-orbit interaction in a nonparaxial light beam. We also numerically quantify the relative contributions of the SAM and OAM of light to the IFE in a thin gold film illuminated by different focused beams carrying SAM and/or OAM. The OAM of light provides an additional degree of freedom in the control of the IFE and resulting optomagnetic field, thus potentially impacting various research fields, including all-optical magnetization switching and spin-wave excitation.