Magnetic non-volatile flip-flop with spin-Hall assistance

A novel multi-bit non-volatile flip-flop (NVFF) written by spin-Hall-assisted spin-transfer torque (STT) is proposed. This NVFF employs perpendicular-anisotropy MTJs and requires an STT current combined with a spin-Hall current to write the data. Thanks to the assistance of spin-Hall effect (SHE), the incubation delay required by the conventional STT switching can be eliminated to achieve fast operation. Our proposed NVFF uses multi-bit architecture and shows high-density and low-energy advantages over hybrid NV/volatile FFs in the application of the NV register file. Simulation results show that the proposed spin-Hall-assisted NVFF saves similar to 31% storage density and similar to 32% energy dissipation compared with the conventional STT-NVFF. Moreover, the reliability of MTJ barrier is enhanced due to the reduction of the write voltage.