Two-bit multi-level spin orbit torque MRAM with the fully one-step write operation

As an emerging non-volatile memory technology, the spin orbit torque magnetic random access memory (SOT-MRAM) has attracted intensive research interest due to its advanced performance. However, the binary storage feature of the SOT-MRAM has become one of the obstacles. In this paper, we present a study of two-bit multi-level SOT-MRAM where two canted in-plane-anisotropy magnetic tunnel junctions (MTJs) store a pair of data. Compared with the previous schemes of multi-level SOT-MRAMs, our proposal enables fully one-step writing without the need of the preset operation. Micromagnetic simulation is performed to validate the functionality of the proposed multi-level cell (MLC) SOT-MRAM, meanwhile, the details of magnetization switching are clearly shown. Simulation results also demonstrate that the device could accomplish the magnetization switching at the sub-nanosecond speed and continuously decreasing power consumption with the size scaling down. In addition, the dipolar field between two cells has little influence on the switching process.