Proposal of a multi-bit cell scheme for spin-orbit torque MRAM array to implement 16 Boolean logic operations

Magnetic random access memory (MRAM) is a promising applicant for universal memory in the post-Moore age, due to its beneficial characteristics in terms of energy efficiency, integration, and endurance. Spin-orbit torque (SOT) MRAM for logic-in-memory (LIM) is a highly anticipated method for processing-in-memory (PIM) to address the von Neumann bottleneck. We present a flexible SOT-MRAM array cell scheme capable of storing multiple bits and executing 16 complete Boolean logic operations. Two magnetic tunnel junctions (MTJs) utilizing SOT and voltage-controlled magnetic anisotropy (VCMA) effects, combined with three transistors, form a 3T2M cell capable of four resistance states (2-bit) for data storage, necessitating a minimum average power consumption of 2.483 fJ/bit for writing. The two operational steps of all-electrical modulation, comprising the write and logic operations, are adequate to execute the 16 Boolean logics in situ. These findings may provide a basis for the development of adaptable and programmable LIM techniques for reconfigurable digital PIM architectures.