| AVS 63rd International Symposium & Exhibition | |
| Magnetic Interfaces and Nanostructures | Monday Sessions |
| Session MI+2D+AC-MoM |
| Session: | Chiral Magnetism (8:20-10:20 am)/Magnetism and Spin Orbit Effects at Interfaces and Surfaces: Recent Experimental and Theoretical Advances (10:40 am - 12:00 pm) |
| Presenter: | Axel Hoffmann, Argonne National Laboratory |
| Authors: | W. Jiang, Argonne National Laboratory X. Zhang, The University of Hong Kong, Hong Kong Special Administrative Region of China G. Yu, University of California Los Angeles M.B. Jungfleisch, Argonne National Laboratory J.E. Pearson, Argonne National Laboratory O. Heinonen, Argonne National Laboratory K.L. Wang, University of California Los Angeles Y. Zhou, The University of Hong Kong, Hong Kong Special Administrative Region of China S.G.E. te Velthuis, Argonne National Laboratory A. Hoffmann, Argonne National Laboratory |
| Correspondent: | Click to Email |
Magnetic skyrmions are a perfect example for the ensuing complexity of mesoscale magnetism stemming from competitions between interactions crossing many lengthscales [1]. The interplay between applied magnetic fields, magnetic anisotropies, as well as symmetric and antisymmetric exchange interactions, can stabilize topologically distinct spin textures known as magnetic skyrmions. Due to their topology magnetic skyrmions can be stable with quasi-particle like behavior, and can be manipulated with very low electric currents. This makes them interesting for extreme low-power information technologies [2,3], where data is envisioned to be encoded in topological charges, instead of electronic charges as in conventional semiconducting devices. Recently, we demonstrated the ability of generating and stabilizing magnetic skyrmions at room temperature in Ta/CoFeB/TaOx trilayers, where the broken inversion symmetry gives rise to a net chiral exchange interaction [4,5]. Using spin Hall effects [6] from the Ta layer it is possible to efficiently move these skyrmions with electric currents. Theoretically it is expected that the motion of the skyrmions have a significant transverse component, the skyrmion Hall effect, which is directly related to the topological charge resulting in a net gyrotropic force. Here we demonstrate the direct observation of this transverse motion [7] using magneto-optic Kerr effect imaging. We observe that the skyrmion Hall angle varies continuously from zero just above the depinning threshold until 15º for current densities up to 107 A/cm2. This gradual variation of the skyrmion Hall angle indicates the changing competition between pinning and gyrotropic forces as the skyrmion motion transitions from the creep to the flow regime. The maximum observed Hall angle is in good agreement with theoretical expectations.
This work was supported by the U.S. Department of Energy, Office of Science, Materials Sciences and Engineering Division. Lithographic patterning was carried out at the Center for Nanoscale Materials, which is supported by DOE, Office of Science, BES (#DE-AC02-06CH11357).
References
1. A. Hoffmann and H. Schultheiß, Curr. Opin. Solid State Mater. Sci. 19, 253 (2015)
2. A. Hoffmann and S. D. Bader, Phys. Rev. Appl. 4, 047001 (2015).
3. W. Jiang, et al., AIP Adv. 6, 055602 (2016).
4. W. Jiang, et al., Science 349, 283 (2015).
5. O. Heinonen, et al., Phys. Rev. B 93, 094407 (2016).
6. A. Hoffmann, IEEE Trans. Magn. 49, 5172 (2013).
7. W. Jiang, et al., arXiv:1603.07393.