Micromagnetics of magnetic chemical modulations in soft-magnetic cylindrical nanowires

©2022 American Physical Society We acknowledge support from the French RENATECH network, the team of the Nanofab platform (CNRS Neel institut) , and the CNRS-CEA METSA French network (FR CNRS 3507) . The project received financial support from the French National Research Agency (Grant No. ANR-17-CE24-0017-01; MATEMAC-3D) , from the Spanish MCIN/AEI/10.13039/501100011033 under Grant No. PID2020-117024GB-C43, and from the Comunidad de Madrid (Spain) through the project NanoMagCOST (CM S2018/NMT-4321) . S.R.-G. gratefully acknowledges the financial support of the Alexander von Humboldt Foundation.
We analyze the micromagnetics of short longitudinal modulations of a high-magnetization material in cylindrical nanowires made of a soft-magnetic material of lower magnetization such as permalloy, combining magnetic microscopy, analytical modeling, and micromagnetic simulations. The mismatch of magnetization induces curling of magnetization around the axis in the modulations, in an attempt to screen the interfacial magnetic charges. The curling angle increases with modulation length, until a plateau is reached with nearly full charge screening for a specific length scale delta(mod), larger than the dipolar exchange length of any of the two materials. The curling circulation can be switched by the Oersted field arising from a charge current with typical magnitude 10(12) A/m(2) for a diameter of similar to 100 nm, and reaching a maximum for delta(mod).
Ministerio de Ciencia e Innovación (MICINN)
Comunidad de Madrid
Agence Nationale de la Recherche (ANR)
Centre National de la Recherche Scientifique (CNRS)/CEA
Depto. de Física de Materiales
Fac. de Ciencias Físicas
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