Survey of 360° domain walls in magnetic heterostructures: Topology, chirality and current-driven dynamics

Chirality and current-driven dynamics of topologically nontrivial 360 degrees domain walls (360DWs) in magnetic heterostructures (MHs) are systematically investigated. For MHs with normal substrates, the static 360DWs are Neel-type with no chirality. While for those with heavy-metal substrates, the interfacial Dzyaloshinskii-Moriya interaction (iDMI) therein makes 360DWs prefer specific chirality. Under in-plane driving charge currents, as the direct result of "full-circle" topology a certain 360DW does not undergo the "Walker breakdown"-type process like a well-studied 180 degrees domain wall as the current density increases. Alternatively, it keeps a fixed propagating mode (either steady-flow or precessional-flow, depending on the effective damping constant of the MH) until it collapses or changes to other types of solition when the current density becomes too high. For both modes, modifications to the mobility of 360DWs by iDMI and spin-orbit torque are provided.