Laser-induced torques in metallic ferromagnets

Abstract

We study laser-induced torques in bcc Fe, hcp Co and $L{1}_0$ FePt based on first-principles electronic structure calculations and the Keldysh nonequilibrium formalism. We find that the torques have two contributions, one from the inverse Faraday effect (IFE) and one from the optical spin-transfer torque (OSTT). Depending on the ferromagnet at hand and on the quasiparticle broadening the two contributions may be of similar magnitude or one contribution may dominate over the other. Additionally, we determine the nonequilibrium spin polarization in order to investigate its relation to the torque. We find the torques and the perpendicular component of the nonequilibrium spin polarization to be odd in the helicity of the laser light, while the spin polarization that is induced parallel to the magnetization is helicity-independent. The parallel component of the nonequilibrium spin polarization is orders of magnitude larger than the perpendicular component. In the case of hcp Co we find good agreement between the calculated laser-induced torque and a recent experiment.

References in corpus (5)

• Super-Diffusive Spin-Transport as a Mechanism of Ultrafast Demagnetization
• All-optical control of ferromagnetic thin films and nanostructures
• Maximally Localized Wannier Functions within the FLAPW formalism
• Current-Induced Torques in Magnetic Metals: Beyond Spin Transfer
• Current Induced Order Parameter Dynamics: Microscopic Theory Applied to Co/Cu/Co spin valves

Cited by in corpus (5)

• Laser induced THz emission from femtosecond photocurrents in Co/ZnO/Pt and Co/Cu/Pt multilayers
• Topological Inverse Faraday Effect in Weyl Semimetals
• Giant inverse Faraday effect in Dirac semimetals
• Laser-induced torques in spin spirals
• Theory of unidirectional magnetoresistance and nonlinear Hall effect