Investigation of the Dzyaloshinskii-Moriya interaction and room temperature skyrmions in W/CoFeB/MgO thin films and microwires
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Author(s)
Jaiswal, S.
Litzius, K.
Büttner, F.
Finizio, S.
Raabe, J.
Weigand, M.
Lee, K.
Langer, J.
Ocker, B.
Jakob, G.
Date Issued
July 2017
Journal
Applied Physics Letters
Publisher
AIP Publishing
Citation
Jaiswal, S. et al. “Investigation of the Dzyaloshinskii-Moriya Interaction and Room Temperature Skyrmions in W/CoFeB/MgO Thin Films and Microwires.” Applied Physics Letters 111, 2 (July 2017): 022409 © 2017 Author(s)
Version
Final published version
Abstract
Recent studies have shown that material structures, which lack structural inversion symmetry and have high spin-orbit coupling can exhibit chiral magnetic textures and skyrmions which could be a key component for next generation storage devices. The Dzyaloshinskii-Moriya Interaction (DMI) that stabilizes skyrmions is an anti-symmetric exchange interaction favoring non-collinear orientation of neighboring spins. It has been shown that materials systems with high DMI can lead to very efficient domain wall and skyrmion motion by spin-orbit torques. To engineer such devices, it is important to quantify the DMI for a given material system. Here, we extract the DMI at the Heavy Metal/Ferromagnet interface using two complementary measurement schemes, namely, asymmetric domain wall motion and the magnetic stripe annihilation. By using the two different measurement schemes, we find for W(5 nm)/Co₂₀Fe₆₀B₂₀(0.6 nm)/MgO(2 nm) the DMI to be 0.68 ± 0.05 mJ/m² and 0.73 ± 0.5 mJ/m², respectively. Furthermore, we show that this DMI stabilizes skyrmions at room temperature and that there is a strong dependence of the DMI on the relative composition of the CoFeB alloy. Finally, we optimize the layers and the interfaces using different growth conditions and demonstrate that a higher deposition rate leads to a more uniform film with reduced pinning and skyrmions that can be manipulated by spin orbit torques.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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DOI of Published Version
https://doi.org/10.1063/1.4991360
