November 07, 2022
Minneapolis, United States
Zero field Magnetic Skyrmions in Multilayer Films Stabilized by Interplay of Interlayer Exchange Couplings
Magnetic skyrmions are promising candidates for achieving low-power, next-generation edge computing devices due to their particle-like nature, efficient coupling to electrical and spin currents and room-temperature stability in multilayer films 1. However, in most skyrmion-hosting multilayers, the predominant magnetic textures at zero-field (ZF) are labyrinthine stripes 2. External applied magnetic fields or geometric confinement 3 are typically used to stabilize isolated skyrmions, which limits their practicality.
In this work, we design multilayers comprising three adjoining functional stacks – two repeats of skyrmion-hosting multilayers and a bias layer – coupled by two tunable interlayer exchange couplings (IECs) 4,5. Using Lorentz transmission electron microscopy (LTEM), we demonstrate that these two IECs act as coarse and fine-tuning knobs that determine skyrmion stability and density. With micromagnetic simulations, we elucidate the unique roles played by each of the couplings and establish the advantage of a duo-IEC system in applications. This work establishes and extends the use of IEC as a means of stabilizing and shaping ZF skyrmions and paves the path to skyrmion-based devices.
References 1 A. Fert, N. Reyren, and V. Cros, Magnetic Skyrmions: Advances in Physics and Potential Applications, Nat. Rev. Mater. 2, natrevmats201731 (2017). 2 X. Chen, M. Lin, J. F. Kong, H. R. Tan, A. K. C. Tan, S.-G. Je, H. K. Tan, K. H. Khoo, M.-Y. Im, and A. Soumyanarayanan, Unveiling the Emergent Traits of Chiral Spin Textures in Magnetic Multilayers, Adv. Sci. 9, 2103978 (2022). 3 P. Ho, A. K. C. Tan, S. Goolaup, A. L. G. Oyarce, M. Raju, L. S. Huang, A. Soumyanarayanan, and C. Panagopoulos, Geometrically Tailored Skyrmions at Zero Magnetic Field in Multilayered Nanostructures, Phys. Rev. Appl. 11, 024064 (2019). 4 G. Chen, A. Mascaraque, A. T. N’Diaye, and A. K. Schmid, Room Temperature Skyrmion Ground State Stabilized through Interlayer Exchange Coupling, Appl. Phys. Lett. 106, 242404 (2015). 5 W. Legrand, D. Maccariello, F. Ajejas, S. Collin, A. Vecchiola, K. Bouzehouane, N. Reyren, V. Cros, and A. Fert, Room-Temperature Stabilization of Antiferromagnetic Skyrmions in Synthetic Antiferromagnets, Nat. Mater. 19, 34 (2019).