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The effects of magnetostatic coupling on switching dynamics are investigated for assemblies of patterned disc-shaped magnetic elements using mumax3 micromagnetic simulations. The arrangements of coupled dots were designed using information about the switching fields and reversal dynamics of isolated dots, as well as the magnitude of the magnetic stray fields they generate. The magnetization dynamics for individual dots was examined during a reversal cascade down a linear chain of dots. The magnetization angle fluctuated much more when neighboring dots have opposite magnetization directions, consistent with a lower energy barrier for reversal. The data were analyzed to differentiate thermal and interaction field effects. While many systems of interacting nanomagnets have been analyzed in terms of empirical models, the dynamical energy barrier approach offers a methodology with a more detailed and physically intuitive way to study both simple systems like the chain and more complex assemblies such as artificial spin ice.
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Enhanced Magnetic Anisotropy for Reprogrammable High‐Force‐Density Microactuators
Abstract The precise control of magnetic properties at the microscale has transformative potential in healthcare and human‐robot interaction. This research focuses on understanding the magnetic interactions in nanostructure assemblies responsible for microactuation. By combining experimental measurements and micromagnetic simulations, the interactions in both nanocube and nanochain assemblies are elucidated. Hysteresis measurements and first‐order reversal curves (FORC) reveal that the spatial arrangement of these assemblies governs their collective magnetism. A critical concentration threshold is observed where a transition from ferromagnetic‐like to antiferromagnetic‐like coupling occurs. Leveraging the high uniaxial anisotropy of 1D nanochains, the remanent magnetization of assembled chain structures is maximized for efficient magneto‐mechanical energy transduction. By utilizing an optimized magnetic nanostructure concentration, a flexible film is fabricated, and its significantly enhanced mechanical deformation response to a small magnetic field, surpassing conventional particle‐based samples by a factor of five, is demonstrated. Demonstrating excellent transduction efficiency, visible deformations such as bending and S‐shaped twisting modes are achieved with an applied field of less than 400 Oe. Furthermore, the reprogrammability of the actuator, achieving a U‐shaped bending mode by altering its magnetization profile, is showcased. This research provides valuable insights for designing reconfigurable and effective microactuators and devices at significantly smaller scales than previously possible.
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- Award ID(s):
- 1719875
- PAR ID:
- 10547676
- Publisher / Repository:
- Wiley Online Library
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 34
- Issue:
- 2
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/adfm.202305502
