Single‐Shot Multi‐Level All‐Optical Magnetization Switching Mediated by Spin Transport

All-optical ultrafast magnetization switching in magnetic material thin film without any applied external magnetic field is drawing a lot of attention for the development of future ultrafast and energy efficient magnetic data storage and memories. Indeed it has been shown that femto-second light pulse can be generated and induce magnetization reversal for a large variety of magnetic materials. However until now, only GdFeCo ferrimanget thin film are known to show single pulse magnetization switching. Here we demonstrate that the four possible magnetic configurations of a magnetic spin-valve structure ([Co/Pt] / Cu / GdFeCo) can be access using single femto-second light pulse and could be used as a multi-bit memory cell. Our experimental study reveals that the magnetization switching is mediated by single pulse spin-polarized hot electron generated by the light pulse. Consequently we are proving that ferromagnetic [Co/Pt] can be switched by a single hot electron pulse. These results challenge present understanding