Skyrmion Brownian circuit implemented in continuous ferromagnetic thin film

Abstract

The fabrication of a circuit capable of stabilizing skyrmions is important for the realization of micro- to nano-sized skyrmion devices. Ultralow power Brownian computers have been theoretically proposed and are a promising example of a skyrmion-based device. However, such devices have not been realized as it would require skyrmions to be stabilized and easily movable within a circuit. Skyrmion circuits fabricated by the etching of ferromagnetic films often decrease the dipolar magnetic field stabilizing the skyrmions, thus preventing their formation. In this study, a skyrmion Brownian circuit has been implemented in a continuous ferromagnetic film with patterned SiO2 capping to stabilize the skyrmion formation. The patterned SiO2 capping controls the saturation field of the ferromagnetic layer and forms a wire-shaped skyrmion potential well, which stabilizes skyrmion formation in the circuit. Moreover, using this patterned SiO2 capping, we have implemented a Y-junction hub circuit exhibiting no pinning site at the junction, contrary to conventional etched hubs. Thus, this technique enables the efficient control of skyrmion-based memory and logic devices to move closer toward the realization of Brownian computers.