Two-Terminal Spin-Orbit Torque (SOT) MRAM Demo published in Nature Electronics!
This excellent experimental work, by Noriyuki Sato, Fen Xue, Robert M. White, Chong Bi and Shan X. Wang, explores an interesting idea to achieve ultrafast and high-density magnetoresistive random access memory (MRAM). It is a “hot” memory chip technology being pursued by semiconductor industry worldwide because it is nonvolatile, energy-efficient, and can also spur new-types of in-memory computing and AI chip architectures. The team demonstrated a SOT-MRAM cell based on a CoFeB/MgO magnetic tunnel junction pillar on an ultrathin and narrow Ta underlayer. In this device with only two electrical terminals (as opposed to other SOT-MRAM cell with three terminals and thus lower density) , in-plane and out-of-plane currents are simultaneously generated on application of a voltage, but the switching mechanism is dominated by SOT rather than spin-transfer torque (STT). Intrinsically, SOT switching is significantly faster than STT, and thus considered a prime candidate to next generation MRAM products.