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| Hauptseite > Publikationsdatenbank > Curvature-modulated structural and magnetic properties of thin filmsdeposited onto highly ordered nanosphere arrays |
| Hauptseite > Publikationsdatenbank > Curvature-modulated structural and magnetic properties of thin filmsdeposited onto highly ordered nanosphere arrays |
| Conference Presentation (Invited) | FZJ-2024-04751 |
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2024
Abstract: The magnetic interaction among magnetic nanostructures has garnered significant attention, leading to extensive research on magneticnanocaps. This exciting research trend has motivated us to explore the potential of these structures. We successfully fabricated andcharacterized isolated and interconnected magnetic nanocaps by depositing magnetic thin films on highly ordered arrays of nanospheres. Theuse of curved surfaces as substrates causes lateral variations in film thickness, resulting in varying deposited material properties. Multilayers ofCo/Pd with varying Co thicknesses were deposited using Molecular Beam Epitaxy (MBE) on a flat silicon (Si) substrate and on densely packedtwo-dimensional arrays of silica nanospheres with diameters of 50 nm and 200 nm, formed using an improved drop-casting method [1]. Themagnetic and structural properties of the nanostructures obtained were compared to those of films deposited simultaneously on a bare Sisubstrate (reference film). Both the studied film and the reference film were grown polycrystalline, while their roughness, as observed from X-rayreflectivity, differed significantly. X-ray reflectivity revealed that the reference films displayed well-defined Kiessig oscillations, indicating lowroughness in the deposited films. In contrast, the films on nanospheres conformed to the curvature of the underlying nanospheres and exhibiteda systematic periodic variation, resulting in the absence of Kiessig oscillations. Magnetic measurements using SQUID confirmed the formationof magnetic nanocaps as they exhibited distinct magnetic properties, including a different anisotropy axis direction and a drastically highcoercivity with increasing film thickness, compared to the flat films prepared on a bare Si substrate. Furthermore, Grazing Incidence Small AngleX-ray Scattering (GISAXS) confirms the formation of a well-aligned, uniform nanosphere distribution. Additionally, the depth-resolved profile ofthe magnetization was studied using Polarized Neutron Reflectivity (PNR). The overall results, the magnetic and structural properties of the thinfilms were correlated as a function of film thickness and nanosphere radius.SEM and GISAXS of (left) densely packed two-dimensional arrays of monodisperse spherical silica particles and (right) self-assembled particle arrays after magnetic film depositionReferences[1] A. Qdemat, et.al., RSC Adv., 10 (2020) 18339-18347
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