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Chiral Spin Bobbers in Exchange-Coupled Hard-Soft Magnetic Bilayers



X. H. Zhang, T. R. Gao, L. Fang, S. Fackler, Julie Borchers, Brian Kirby, Brian B. Maranville, S. E. Lofland, A. T. N'Diaye, E. Arenholz, A. Ullah, J. Cui, R. Skomski, Ichiro Takeuchi


The spin structure of exchange-coupled MnBi:Co-Fe bilayers is investigated by X-ray magnetic circular dichroism (XMCD), polarized neutron reflectometry (PNR), and micromagnetic simu-lations. The purpose of the present research is two-fold. First, the current search for new permanent-magnet materials includes hard-soft nanocomposites, and the analysis of coercivity mechanisms in these structures is an important aspect of this quest. Second, topological micro-magnetic structures such as skyrmions have recently become of intense fundamental and applied research, for example in the context of spin-based electronics. We find that the magnetization reversal of the MnBi:Co-Fe bilayer structure involves a curling-type twisting of the magnetization in the film plane. This curling in the exchange-coupled hard-soft magnetic bilayers is reminiscent of chiral spin structures known as bobbers and, in fact, establishes a new type of skyrmionic spin structure.


Permanent magnet, Neutron reflectivity, Chiral bobbers, Exchange coupling


Zhang, X. , Gao, T. , Fang, L. , Fackler, S. , Borchers, J. , Kirby, B. , Maranville, B. , Lofland, S. , N'Diaye, A. , Arenholz, E. , Ullah, A. , Cui, J. , Skomski, R. and Takeuchi, I. (2021), Chiral Spin Bobbers in Exchange-Coupled Hard-Soft Magnetic Bilayers, arxiv, [online],,-Xiaohang%20Zhang%2C%20Tieren&text=The%20spin%20structure%20of%20exchange,present%20research%20is%20two%2Dfold. (Accessed May 21, 2024)


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Created November 17, 2021, Updated November 29, 2022