A Multi-domain Magneto Tunnel Junction for Racetrack Nanowire Strips

Domain-wall memory (DWM) has SRAM class access performance, low energy, high endurance, high density, and CMOS compatibility. Recently, shift reliability and processing-using-memory (PuM) proposals developed a need to count the number of parallel or anti-parallel domains in a portion of the DWM nanowire. In this paper we propose a multi-domain magneto-tunnel junction (MTJ) that can detect different resistance levels as a function of a the number of parallel or anti-parallel domains. Using detailed micromagnetic simulation with LLG, we demonstrate the multi-domain MTJ, study the benefit of its macro-size on resilience to process variation and present a macro-model for scaling the size of the multi-domain MTJ. Our results indicate scalability to seven-domains while maintaining a 16.3mV sense margin.