Existence of in-Plane Magnetic Skyrmion and its Motion under Current Flow

A magnetic skyrmion usually refers to a twisted spin texture in a uniformly aligned magnetization state. Such spin texture is protected by topology, which makes the skyrmion a stable texture under small perturbations. Thus, skyrmions have attracted great interest for possible applications as an ideal information carrier. Most magnetic skyrmion studies have focused on perpendicularly magnetized systems, where the skyrmion topological charge is determined by the relative orientation between the core and outer perpendicular magnetization directions. Thus, skyrmions with opposite signs of topological charges do not seem to coexist in the same magnetic domain. Here we show that there also exists a different type of magnetic skyrmion with surrounding spins that are uniformly aligned to the in-plane direction. A clear feature of this in-plane skyrmion is that skyrmions with opposite signs of topological charges can coexist with each other. Proper choice of magnetization and Dzyaloshinskii-Moriya interaction leads to a window for the existence of this in-plane skyrmion. These findings demonstrate the inherent possibility of a double-bit transfer in a single magnetic wire, which is not possible in a perpendicularly magnetized system.