| 1. |
- Hamann, Christine, et al.
(författare)
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Competing magnetic interactions in exchange-bias-modulated films
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 81:2, s. 024420-
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Tidskriftsartikel (refereegranskat)abstract
- The magnetization reversal in stripelike exchange-bias-patterned Ni81Fe19/IrMn thin films was investigated by complementary inductive and high-resolution magneto-optical magnetometry, magneto-optical Kerr microscopy, and polarized neutron reflectometry to clarify the effects of competing interfacial exchange-bias and lateral interface contributions. Structures of varying ferromagnetic layer thickness and stripe period were analyzed systematically at the frozen-in domain state of oppositely aligned stripe magnetization. For all samples the mean magnetization of the magnetic hybrid structures was found to be aligned nearly orthogonally with respect to the stripe axis and the set exchange-bias direction. Due to the interaction of interfacial coupling, exchange, and magnetostatic energy contributions, the opening angle of neighboring stripe magnetizations increases with decreasing ferromagnetic layer thickness and increasing stripe period. The experimental observations are in agreement with an earlier proposed model for designing micropatterned exchange-bias films.
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| 2. |
- Saini, Apurve, et al.
(författare)
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Layering of magnetic nanoparticles at amorphous magnetic templates with perpendicular anisotropy
- 2020
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 16:33, s. 7676-7684
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Tidskriftsartikel (refereegranskat)abstract
- We reveal the assembly of magnetite nanoparticles of sizes 5 nm, 15 nm and 25 nm from dilute water-based ferrofluids onto an amorphous magnetic template with out-of-plane anisotropy. From neutron reflectometry experiments we extract density profiles and show that the particles self-assemble into layers at the magnetic surface. The layers are extremely stable against cleaning and rinsing of the substrate. The density of the layers is determined by and increases with the remanent magnetic moment of the particles.
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| 3. |
- Theis-Broehl, Katharina, et al.
(författare)
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Self assembly of magnetic nanoparticles at silicon surfaces
- 2015
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 11:23, s. 4695-4704
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Tidskriftsartikel (refereegranskat)abstract
- Neutron reflectometry was used to study the assembly of magnetite nanoparticles in a water-based ferrofluid close to a silicon surface. Under three conditions, static, under shear and with a magnetic field, the depth profile is extracted. The particles have an average diameter of 11 nm and a volume density of 5% in a D2O-H2O mixture. They are surrounded by a 4 nm thick bilayer of carboxylic acid for steric repulsion. The reflectivity data were fitted to a model using a least square routine based on the Parratt formalism. From the scattering length density depth profiles the following behavior is concluded: the fits indicate that excess carboxylic acid covers the silicon surface and almost eliminates the water in the densely packed wetting layer that forms close to the silicon surface. Under constant shear the wetting layer persists but a depletion layer forms between the wetting layer and the moving ferrofluid. Once the flow is stopped, the wetting layer becomes more pronounced with dense packing and is accompanied by a looser packed second layer. In the case of an applied magnetic field the prolate particles experience a torque and align with their long axes along the silicon surface which leads to a higher particle density.
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| 4. |
- Theis-Broehl, Katharina, et al.
(författare)
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Self-assembly of Magnetic Nanoparticles in Ferrofluids on Different Templates by Neutron Reflectometry
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This article reviews the self-assembly of magnetite nanoparticles onto solid surfaces. We focus on neutron reflectometry studies providing information on the density and magnetization profiles of buried interfaces. Specific attention is given to the near-interface wetting layer and to examples of magnetite nanoparticles on a hydrophilic silicon crystal, one coated with (3-Aminopropyl)triethoxysilan, and finally one with a magnetic film with out-of-plane magnetization.
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| 5. |
- Theis-Broehl, Katharina, et al.
(författare)
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Self-Assembly of Magnetic Nanoparticles in Ferrofluids on Different Templates Investigated by Neutron Reflectometry
- 2020
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:6
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Forskningsöversikt (refereegranskat)abstract
- In this article we review the process by which magnetite nanoparticles self-assemble onto solid surfaces. The focus is on neutron reflectometry studies providing information on the density and magnetization depth profiles of buried interfaces. Specific attention is given to the near-interface "wetting" layer and to examples of magnetite nanoparticles on a hydrophilic silicon crystal, one coated with (3-Aminopropyl)triethoxysilane, and finally, one with a magnetic film with out-of-plane magnetization.
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