Single-shot switching in Tb/Co-multilayer based nanoscale magnetic tunnel junctions

[Display omitted] •Optical writing and electrical reading of magnetic states within nanoscale ferromagnetic tunnel junctions.•Downscaling of the perpendicularly magnetized nanodevices while retaining the desired functionalities.•Correlation between the switching probability, magnetic anisotropy, and the diameter of the nanodevices.•Probing the depth-resolved hysteresis and time-resolved magnetization dynamics in a full stack magnetic tunnel junction film. Magnetic tunnel junctions (MTJs) are elementary units of magnetic memory devices. For high-speed and low-power data storage and processing applications, fast reversal of the magnetization by an ultrashort laser pulse is extremely important. We demonstrate single-shot switching of Tb/Co-multilayer based nanoscale MTJs by combining the optical writing and the electrical read-out methods. A 90-fs-long laser pulse switches the magnetization of the storage layer (SL). The change in the tunneling magnetoresistance (TMR) between the SL and a reference layer (RL) is probed electrically across the oxide barrier. Single-shot switching is demonstrated by varying the cell diameter from 300 nm to 20 nm. The anisotropy, magnetostatic coupling, and switching probability exhibit cell-size dependence. By suitable association of laser fluence and magnetic field, successive commutation between high-resistance and low-resistance states is achieved. The nature of the magnetization reversal of both SL and RL in a continuous film is probed with a depth-resolved magneto-optical Kerr effect (MOKE) magnetometry. The ultrafast dynamics in the continuous full-MTJ stack is investigated with the time-resolved pump–probe technique. Our experimental findings provide strong support for the growing interest in ultrafast spintronic devices.