Laser induced precessional switching in exchange biased NiFe/FeMn bilayers

Laser pulse induced field assisted precessional switching in exchange coupled mesoscopic NiFe/FeMn striplines has all-optically been triggered and magneto-optically observed in real time with switching times down to 500 ps. A fast decoupling of the exchange bias bilayer launches coherent precession of the magnetization of the ferromagnetic layer of the exchange bias system. By properly choosing the initial equilibrium orientation the optical unpinning of the bilayer can induce complete magnetization switching. Stroboscopic time domain imaging of the switching event has been realized by a sophisticated synchronization scheme of a magnetic preset pulse and both the optical pump and probe pulses, respectively. The observed laser assisted switching can be well described by the Landau-Lifshitz-Klaasen-van Peppen equation combining precessional and thermally activated spin dynamics.