Inverse Faraday Effect Revisited

The inverse Faraday effect is usually associated with circularly polarized laser beams. However, it was recently shown that it can also occur for linearly polarized radiation [1]. The quasi-static axial magnetic field by a laser beam propagating in plasma can be calculated by considering both the spin and the orbital angular momenta of the laser pulse. A net spin is present when the radiation is circularly polarized and a net orbital angular momentum is present if there is any deviation from perfect rotational symmetry. This orbital angular momentum has recently been discussed in the plasma context [2], and can give an additional contribution to the axial magnetic field, thus enhancing or reducing the inverse Faraday effect. As a result, this effect that is usually attributed to circular polarization can also be excited by linearly polarized radiation, if the incident laser propagates in a Laguerre-Gauss mode carrying a finite amount of orbital angular momentum.\\[4pt] [1] S. ALi, J.R. Davies and J.T. Mendon\c{c}a, \textit{Phys. Rev. Lett.}, {\bf 105}, 035001 (2010).\\[0pt] [2] J. T. Mendon\c{c}a, B. Thid\'{e}, and H. Then, \textit{Phys. Rev. Lett.} \textbf{102}, 185005 (2009).