Spin-orbit torque assisted magnetization reversal of 100 nm-long vertical pillar

Abstract

Long vertical pillars, with a width of the order of nanometers and with perpendicular shape anisotropy (PSA), have high thermal stability. The advantage of using longer pillars is that they can increase the memory areal density while maintaining robust thermal stability. The current-induced magnetization reversal of long pillars is a significant challenge in spintronic applications such as high-density magnetic memories. However, the magnetization of pillars that are more than 100 nm long has never been reversed by spin-orbit torque (SOT) or spin injection from another ferromagnet (FM). Against this background, we propose a novel magnetization reversal method for pillars based on both SOT and spin transfer torque without using a FM for spin injection. Furthermore, this SOT-assisted method significantly reduces the reversal time, as was demonstrated by micromagnetic simulation. Using a spin-polarized current and SOT, the magnetization was reversed in pillars with length ⩾100 nm. The magnetization of pillars with PSA and those with both high perpendicular magnetic anisotropy and PSA was successfully reversed. The findings of this study are physically novel and significant for practical applications. Consequently, the proposed new writing scheme paves the way for next-generation spintronic devices.