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 VO2 into the specific spin valve, where a switchable ultra-short polarized electron pulse by thermally triggering the phase transition of VO2 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 VO2 in its metallic state while it is blocked in its insulating state. Additionally, the change on electrical and optical properties of VO2 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.

Automated summary

All-optical switching, a technology that allows ultrafast magnetization reversal of magnetic thin films without the need for external magnetic or electrical fields, has great potential for ultrafast and low-energy magnetic devices. In this study, a new functionality is introduced by incorporating a thin VO2 film into a specific spin valve, enabling the control of the ferromagnet's switching through thermally-triggered phase transition of VO2 and the generation of switchable ultra-short polarized electron pulse.