Abstract
Magnetic domain wall motion could be the key to the next generation of data storage devices, shift registers without mechanically moving parts. Various concepts of such so-called ‘racetrack memories’ have been developed, but they are usually plagued by the need for high current densities or complex geometrical requirements. We introduce a new device concept, based on the interfacial Dzyaloshinskii-Moriya interaction (DMI), of which the importance in magnetic thin films was recently discovered. In this device the domain walls are moved solely by magnetic fields. Unidirectionality is created utilizing the recent observation that the strength with which a domain wall is pinned at an anisotropy barrier depends on the direction of the in-plane field due to the chiral nature of DMI. We demonstrate proof-of-principle experiments to verify that unidirectional domain-wall motion is achieved and investigate several material stacks for this novel device including a detailed analysis of device performance for consecutive pinning and depinning processes.
Highlights
Driven by the ever increasing demand for denser and faster data storage media, novel memory devices are being explored by the spintronics community
We were inspired by the recent observation that a combination of an in-plane magnetic field and interfacial Dzyaloshinskii-Moriya interaction (DMI) causes a significant asymmetry in the domain-wall depinning field at an anisotropy barrier[21]
It is demonstrated that unidirectional motion of multiple domains walls is achieved for alternating in-plane and out-of-plane field combinations, fully in line with the underlying physics of DMI-induced depinning asymmetry
Summary
Driven by the ever increasing demand for denser and faster data storage media, novel memory devices are being explored by the spintronics community. Drawbacks of such ratchet compared to the conventional racetrack are that the information can only be moved in one direction, and the complex structural modulation makes it unlikely to be implemented in industry Another interesting idea is to make use of the precession torque that a magnetic field exerts on the magnetic moments inside the domain wall[12, 13]. The underlying physical phenomenon is the Dzyaloshinskii-Moriya interaction (DMI), which stabilizes chiral Néel walls, leading to a difference in DW energy (and a different DW velocity) when parallel or antiparallel in-plane magnetic fields are applied This antisymmetric type of exchange interaction is intensively researched because of its importance for spin-orbit torque driven domain wall motion[5, 18] and for the formation of magnetic skyrmions[19, 20]. This is an important step towards a further understanding of the physics processes and, though many technical challenges remain regarding scaling down and the control of orthogonal magnetic fields, the potential implementation in future memory devices
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
