Impact of stray field on spin-transfer torque and voltage controlled magnetic anisotropy assisted spin-orbit torque magnetic RAMs

Abstract Spin–orbit torque magnetic random-access memory (SOT-MRAM) has recently garnered significant attention as an emerging non-volatile memory technology.
While designing SOT-MRAM arrays, it is essential to account for magnetic coupling with neighboring SOT-MRAMs (inter-cell), as well as within the MRAM itself (intra-cell), to assess their overall performance characteristics. In this work, we investigate the impact of intra- and inter-cell magnetic coupling induced stray field on the switching characteristics of SOT-MRAMs. The magnetization dynamics of SOT-MRAMs have been analyzed based on the Landau-Lifshitz-Glibert equation using a micro-magnetic simulation framework, while the Write/Read performances have been evaluated by solving the two-dimensional Fokker-Planck equation. Simulation results show that both during spin-transfer torque (STT)-assisted and voltage-controlled magnetic anisotropy (VCMA)-assisted switching, intra-cell coupling has a greater impact than inter-cell coupling. In the presence of stray field, the Write performance improves in one switching direction or the other depending on reference layer magnetization, whereas the Read operation is essentially unaffected. Furthermore, between the two switching techniques, VCMA-assisted switching demonstrates better performances during Write operations -- both in the presence and absence of magnetic coupling.