On/Off Ultra‐Short Spin Current for Single Pulse Magnetization Reversal in a Magnetic Memory Using VO₂ Phase Transition

Ultrafast magnetization reversal of magnetic thin films induced by one single femtosecond laser light pulse, without any applied magnetic nor electrical field, known as all‐optical switching has become one of the most attractive technologies for prospective ultrafast and low‐energy magnetic devices. A single femtosecond laser pulse switching of a ferromagnet in specific spin valves, driven by electron pulse originating from ultrafast demagnetization of a ferrimagnetic layer, has been recently demonstrated. This opens the way to ultrafast and energy‐efficient writing for magnetic memory. Here, a new functionality is presented through introducing a thin VO 2 into the specific spin valve, where a switchable ultra‐short polarized electron pulse by thermally triggering the phase transition of VO 2 to dynamically control the switching of the ferromagnet is experimentally achieved. It is demonstrated that the generated ultra‐short electron pulse can be free to pass through the VO 2 in its metallic state while it is blocked in its insulating state. Additionally, the change on electrical and optical properties of VO 2 during the phase transition leads to various possible magnetic states. On/off ultra‐short spin current controlled by phase transition paves the way to address specific ultra‐fast spintronic devices in large array devices.