Roles of heating and helicity in ultrafast all-optical magnetization switching in TbFeCo

Using the time-resolved magneto-optical Kerr effect method, helicity dependent all-optical magne- tization switching (HD-AOS) is observed in ferrimagnetic TbFeCo films. Our results reveal the individual roles of the thermal and nonthermal effects after a single circularly polarized laser pulse. The evolution of this ultrafast switching occurs over different time scales, and a defined magnetization reversal time of 460 fs is shown—the fastest ever observed. Micromagnetic simulations based on a single macro-spin model, taking into account both heating and the inverse Faraday effect, are performed which reproduce HDAOS demonstrating a linear path for magnetization reversal.