Sub-ns Switching and Cryogenic-Temperature Performance of Mo-Based Perpendicular Magnetic Tunnel Junctions

Mo-based perpendicular magnetic tunnel junctions (Mo-pMTJs) can outperform mainstream Ta-pMTJs in terms of perpendicular magnetic anisotropy (PMA) and thermal tolerance. However, studies on the ultrafast switching of Mo-pMTJ devices remain limited. In addition, although pMTJ devices have potential to function as cryogenic memory cells, there has been no report on the performance of Mo-pMTJs at low temperatures until now. In this Letter, Mo-pMTJs were prepared with strong PMA and patterned into nanoscale devices. Scanning transmission electron microscopy was employed to characterize the device lateral dimension and structure integrity. Systematic probability measurements were conducted under various pulse widths and current densities. On the ultrafast timescale down to sub-ns, the switching is confirmed to enter the precessional regime. The optimization of the switching energy is discussed. Moreover, we investigate the magneto-transport properties and switching of Mo-pMTJs at low temperatures down to 2 K. The feasibility of utilizing Mo-pMTJ devices in cryogenic memory is verified through this work.