Double spin-torque magnetic tunnel junction devices for last-level cache applications

We experimentally demonstrate reliable 300 ps switching in arrays of 35 nm double spin-torque magnetic tunnel junctions (DS-MTJs), and also demonstrate a new free-layer design with improved activation energy and magnetoresistance. We establish a new method to characterize the DS-MTJ devices for materials feedback, by introducing and experimentally verifying a simple device-physics model. The model and data show that, compared to a single MTJ (SMTJ), the DS-MTJ has lower switching current, faster switching speed, and better dependence on resistance-area product (RA), meeting key requirements for last-level cache.