Seminar on 21 March 2019

Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
Magnetic moment generation in small gold nanoparticles via the plasmonic inverse Faraday effect
at 13:00 in Seminar room F052

During the seminar, i will present a recent work where we theoretically investigate the ultrafast creation of a magnetic moment in gold nanoparticles by circularly polarized laser light. To this end, we describe the collective electron dynamics in gold nanoparticles using a semiclassical approach based on a quantum hydrodynamic model that incorporates the principal quantum many-body and nonlocal effects, such as the electron spill-out, the Hartree potential, and the exchange and correlation effects. We use a variational approach to investigate the breathing and the dipole dynamics induced by an external electric field. We show that gold nanoparticles can build up a static magnetic moment through the interaction with a circularly polarized laser field. We analyze that the responsible physical mechanism is a plasmonic, orbital inverse Faraday effect, which can be understood from the time-averaged electron current that contains currents rotating on the nanoparticles surface. The computed laser-induced magnetic moments are sizeable, of about 0.35 muB/atom for a laser intensity of 450 GW/cm2 at plasmon resonance.