Theory Department

Max Planck Institute of Microstructure Physics

Bose, Th., Berakdar, J.

Nonlinear magneto-optical response to light carrying orbital angular mometum
Journal of Optics **16**, (12),pp 125201/1-13 (2014)
We predict a nonthermal magneto-optical effect for magnetic insulators subject to intense light
carrying orbital angular momentum (OAM). Using a classical approach to second harmonic
generation in nonlinear media with specific symmetry properties we predict a significant
nonlinear contribution to the local magnetic field triggered by light with OAM. The resulting
magnetic field originates from the displacement of electrons driven by the electrical field (with
amplitude E_{0}) of the spatially inhomogeneous optical pulse, modeled here as a
Laguerre-Gaussian beam carrying OAM. In particular, the symmetry properties of the irradiated
magnet allow for magnetic field responses which are second-order ( ∼ E^{2}_{0}) and fourth-order
( ∼ E^{4}_{0}) in electric-field strength and have opposite signs. For sufficiently high laser intensities, terms ∼ E^{4}_{0} dominate and generate magnetic field strengths which can be as large as several Tesla. Moreover, changing the OAM of the laser beam is shown to determine the direction of the total light-induced magnetic field, which is further utilized to study theoretically the nonthermal magnetization dynamics.

TH-2014-50