Extended Data Fig. 1: STT-MRAM device.
From: A lossless and fully parallel spintronic compute-in-memory macro for artificial intelligence chips
(a) Vertical structure of MTJ. RL: reference layer, which has a fixed magnetization. FL: free layer, whose magnetization can switch between parallel (P) and antiparallel (AP) orientations relative to the reference layer. HL: hard layer, which possesses strong perpendicular magnetic anisotropy (PMA). (b) Measured I-V curve of the MTJ’s magnetic resistive switching. The SEM image shows the MTJ’s critical diameter of 78 nm. (c) Measured R-V curve of the MTJ’s magnetic resistive switching, showing a clear resistance change between high-resistance (anti-parallel, AP) and low-resistance (parallel, P) states. The TMR ratio is approximately 170% at 0.1 V. TMR: Tunnel Magneto-Resistance, TMR = (RAP – RP) / RP * 100%. (d) Measured distribution of state switching voltages (VAP→P, VP→AP), with a mean VAP→P of 0.461 V (standard deviation σ = 0.029 V, CV = 6.3%) and a mean VP→AP of –0.299 V (σ = 0.020 V, CV = 6.7%). (e) Resistance distributions of the RP and RAP, where the mean RAP is 9199.2 Ω (σ = 480.7 Ω, CV = 5.2%) and the mean RP is 3363.7 Ω (σ = 171.8 Ω, CV = 5.1%). (f) Measured TMR distribution, with a mean of 173.5% (σ = 3.9%, CV = 2.2%). CV: Coefficient of Variation, CV = standard deviation (σ) / mean (μ) * 100%.
