Experimental Demonstration of Field-Free STT-Assisted SOT-MRAM (SAS-MRAM) With Four Bits per SOT Programming Line

SAS-MRAM has been proposed as a potential last-level cache SRAM replacement owing to its high speed (similar to 1 ns), high cell density, and high endurance characteristics. Here, we report a first-of-its-kind experimental demonstration of simultaneous switching of 4 magnetic tunnel junctions (MTJs) with different polarity on the same spin-orbit torque (SOT) write line. We experimentally verify the novel SAS-MRAM writing scheme which overcomes the unique disturb modes found in the shared SOT line structure and enables simultaneous, field-free switching of multiple MTJs. The non-volatility of SAS-MRAM promises advantages in energy efficient computing applications such as edge AI over SRAM.