Control of Skyrmions in Confined Devices for Multistate Memory Application

The dynamics and stability of magnetic skyrmions within a nano-track with multiple confinements are investigated. The motion of a single skyrmion under a polarized electric current is studied. By adjusting the current magnitude and pulse width, the study reveals the possibility of pinning the skyrmion in each confinement. The depinning of the skyrmion from the top confinement requires two pulses with adjustable time delay while a single pulse is enough to depin it for the case of bottom confinement. The study is extended to two skyrmions and it is found that once a skyrmion is pinned in one confinement, the second one stabilizes in the nearest available empty state. The results show that a multistate device could be obtained with the existence of only one skyrmion per state. This scheme offers an accurate way of controlling the resistance of the devices and thus could be used for multistate memory devices. Toward a multistate skyrmionic device, a stepped nano-track with confinements is proposed. The adjustment of the current magnitude and its duration enables the displacement of the skyrmion at any position. It is possible to control the flow of more than one skyrmion with the pinning of each one in a confined region.image (c) 2024 WILEY-VCH GmbH