Tan, H. K., Lim, R. J. J., Seng, H. L., Shanmugam, J., Ko, H. Y. Y., Cheng, X. M., … Ho, P. (2021). Intermixing induced anisotropy variations in CoB-based chiral multilayer films. Journal of Physics D: Applied Physics, 54(35), 354003. doi:10.1088/1361-6463/ac09b6
Abstract:
We examine the atomic intermixing phenomenon in three distinct amorphous CoB-based multilayer thin film platforms — Pt/CoB/Ir, Ir/CoB/Pt and Pt/CoB/MgO — which are shown to stabilise room-temperature chiral magnetic textures. Intermixing occurs predominantly between adjacent metallic layers. Notably, it is stack-order dependent, and particularly extensive when Ir sits atop CoB. Intermixing induced variations in magnetic properties are ascribed to the formation of magnetic dead layer arising from CoIr alloying in the metallic stacks. It also produces systematic variations in saturation magnetization, by as much as 30%, across stacks. Crucially, the resulting crossover CoB thickness for the transition from perpendicular to in-plane magnetic anisotropy differs by more than 2× across the stacks. Finally, with thermal annealing treatment over moderate temperatures of 150–300 °C, the magnetic anisotropy increases monotonically across all stacks, coupled with discernibly larger Hc for the metallic stacks. These are attributed to thermally induced CoPt alloying and MgO crystallization in the metallic and oxide stacks, respectively. Remarkably, the CoB in the Pt/CoB/MgO stacks retains its amorphous nature after annealing. Our results set the stage for harnessing the collective attributes of amorphous CoB-based material platforms and associated annealing processes for modulating magnetic interactions, enabling the tuning of chiral magnetic texture properties in ambient conditions.
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Publisher Copyright
Funding Info:
This research / project is supported by the A*STAR - SpOT-LITE programme
Grant Reference no. : A18A6b0057
Description:
This is the Accepted Manuscript version of an article accepted for publication in Journal of Physics D: Applied Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/1361-6463/ac09b6