Low-Energy Picosecond Magnetic Switching for Synthetic Ferrimagnetic Free Layer Utilizing the Electric-Field-Tuned RKKY Effect

The precessional switching mechanism has governed the magnetic switching in magnetic tunnel junctions (MTJs) in the sub-nanosecond range, which exponentially increases the switching current density of magnetic random access memory (MRAM). Thus, there needs to be an alternative switching mechanism with much higher energy efficiency to bring down the switching current density significantly and make the MRAM compatible with high-speed L1/2 - static random access memory (SRAM) at sub-nanosecond range. Using the recent discovered external electric field ( E -field) tunable Ruderman-Kittel-Kasuya-Yosida (RKKY) phenomena in a synthetic ferrimagnet (E-SFi), we propose a totally different Chrysanthemum-like switching mechanism to realize a low-energy picosecond writing MRAM design, which breaks the precessional switching mechanism at picosecond region. And our results show that the critical switching current density can be significantly reduced by one order of magnitude compared to that of a conventional MTJ design down to 100 ps. In addition, we study the robustness of the asynchronous conditions between the charge current pulse and the E -field pulse for its practical applications.