SHE-NVFF: Spin Hall Effect-Based Nonvolatile Flip-Flop for Power Gating Architecture

A novel nonvolatile flip-flop (NVFF) using a magnetic tunnel junction (MTJ) is presented for power gating architecture. The proposed NVFF exploits spin Hall effect (SHE) for fast and low-power data backup into MTJs before the power is gated off. Owing to the high spin injection efficiency of SHE, the estimated write current for backup operation is lower than 40 μA. Due to the low write current requirement, we do not introduce a dedicated write driver circuit. Instead, we utilize the cross-coupled inverters in the slave latch to perform the backup operation, resulting in low area overhead. The simulation results show 10× improvement in backup energy when compared with previous works on spin transfer torque-based NVFFs.