Versatility of Spin-Logic and High-Density Multistate Memory Enabled by a Single Spin–Orbit Torque Device

Non-volatile devices based on the spin–orbit torque (SOT) mechanism are suitable for in-memory logic operations. The current objective is to enhance the memory density of memory cells while performing logic operations within the same memory unit. The present study demonstrates that integrating SOT with an out-of-plane magnetic field effectively achieves multiple magnetic states in perpendicularly magnetized heterostructures. This study further explores this approach, experimentally demonstrating versatile logic operations within a single SOT device using W/Pt/Co/AlO_x heterostructures. Our results show that multistate tuning by SOT integration with an out-of-plane magnetic field enables versatility in logic operations, including AND, OR, NOR, NAND, and Always ON, within a single device. Additionally, we found that the careful selection of input logic operations allows multiple configurations to achieve the same logic function within a single memory device. To enhance the multistate memory density, we proposed and experimentally verified a two-step writing process, achieving the highest reported multistate memory density in SOT-based memory devices. These findings highlight the potential of integrating SOT and magnetic field effects to realize high-density, multifunctional, in-memory logic devices.