Data-Writing and Shifting Processes Toward a Vertical Domain Wall Motion Memory

We demonstrate data writing and shifting processes in a double-free-layer nanopillar with perpendicular magnetic anisotropy (PMA). For the data writing process, the magnetization of the lower free layer is switched by injecting in-plane current pulses into the Pt bottom electrode to generate spin-orbit torque (SOT). The written information, i.e., the magnetization direction of the lower free layer, is subsequently transferred to the upper free layer through spin-transfer torque (STT) by injecting out-of-plane current pulses into the nanopillar. Furthermore, we verify that this write-and-shift memory operation can be achieved from different initial magnetization states.