The role of interfacial Dzyaloshinskii–Moriya interaction in different heavy metal-based perpendicular magnetic systems and its application in spintronic devices

The interfacial Dzyaloshinskii–Moriya interaction (DMI) acting as an essential source to stabilize spin textures in ferromagnetic ultrathin films has revealed its significant role in spin–orbit torque (SOT)-driven magnetic switching. Based on a convincing homochiral Néel domain wall model, the in-plane (IP) magnetic field associated with the DMI effect has been confirmed as an essential prerequisite for deterministic SOT-driven switching. Although the presence of the IP field is required, the impact of IP field magnitude combined with the DMI effect on SOT-driven switching in different heavy metals (HMs) has never been considered together. In this research, SOT-induced switching under various IP fields in Pt, W, or Ta/CoFeB/MgO systems has been studied. The results show that the critical threshold current I_C is almost independent of the IP field in the Pt-based structure; however, it significantly decreases with an increase in the IP field in the W- and Ta-based systems. Combining the derived DMI field and the magnetic domain nucleation, it is concluded that the significant difference in DMI fields and the domains' nucleating positions are the main reasons for the above phenomenon. Exploiting the distinct dependent properties of I_C on the IP field, a six resistance state multilevel storage and five programmable spin logic gates are proposed and realized. This study provides insight into the special ability of the SOT effect modulated by the DMI, and also expands an effective way to construct spin-based devices based on this unique spintronic effect.