11 research outputs found
Reduction of magnetostatic interactions in self-organized arrays of nickel nanowires using atomic layer deposition
Ordered arrays of magnetic nanowires are commonly synthesized by
electrodeposition in nanoporous alumina templates. Due to their dense packing,
strong magnetostatic interactions prevent the manipulation of wires
individually. Using atomic layer deposition we reduce the diameter of the pores
prior to electrodeposition. This reduces magnetostatic interactions, yielding
fully remanent hysteresis loops. This is a first step towards the use of such
arrays for magnetic racetrack memories
Observation of Bloch-point domain walls in cylindrical magnetic nanowires
Topological protection is an elegant way of warranting the integrity of
quantum and nanosized systems. In magnetism one example is the Bloch-point, a
peculiar object implying the local vanishing of magnetization within a
ferromagnet. Its existence had been postulated and described theoretically
since several decades, however it has never been observed. We con rm
experimentally the existence of Bloch points, imaged within domain walls in
cylindrical magnetic nanowires, combining surface and transmission XMCD-PEEM
magnetic microscopy. This opens the way to the experimental search for peculiar
phenomena predicted during the motion of Bloch-point-based domain walls
What static and dynamic properties should slalom skis possess? Judgments by advanced and expert skiers
Flexural and torsional rigidity are important properties of skis. However, the flexural and torsional rigidity that lead to optimal performance remain to be established. In the present study, four pairs of slalom skis that differed in flexural and torsional rigidity were tested by advanced and expert skiers. Using a 10-item questionnaire, different aspects of the skis’ performance were rated on a 9-point scale. For each pair of skis, physical measurements were compared with the ratings of the two groups of skiers. Correlations (Spearman) were then determined between (i) different mechanical properties of the skis (static and dynamic), (ii) subjective assessments of the participants, and (iii) properties of the skis and the participants’ assessments. The latter showed that expert skiers rate the aspects of the skis more accurately than advanced skiers. Importantly, expert skiers are particularly sensitive to torsion of the skis. These results suggest that such highly rated elements should be addressed in future ski designs
Programs used to generate the figures in arXiv:1712.03154v2 "The skyrmion-bubble transition in ferromagnetic thin films"
This release contains all the data for the study of the skyrmion-bubble transition in a ferromagnetic thin film including a S factor calculator and programs used to generate the figures
Strong low temperature magnetoelastic effects in template grown Ni nanowires
Arrays of nickel nanowires embedded into polycarbonate membranes were studied by means of ferromagnetic resonance. Large magnetoelastic effects were evidenced in the entire temperature range 4.3-300 K, which were attributed to the thermal expansion coefficients mismatch between the Ni nanowires and the polycarbonate membrane. The resulting magnetoelastic energy was measured as a function of both membrane porosity and diameter of the nanowires. For low volume fractions of Ni in Ni/polycarbonate samples, the magnitude of the magnetoelastic anisotropy may be as high as the shape anisotropy. Conversely, no magnetoelastic effects were observed in permalloy nanowires embedded in the same membranes
Permittivity model for ferromagnetic nanowired substrates
This letter presents the influence of ferromagnetic nanowires on permittivity and losses on a so-filled membrane. For this purpose a theoretical permittivity model has been developed by considering geometrical parameters of the substrate such as the porosity of the membrane and the height of the nanowires. It has been validated by microstrip line measurements on a composite substrate filled with cobalt nanowires. The ferromagnetic nanowires enhance the permittivity, but give no further contribution to the losses beyond the ferromagnetic resonance. This is confirmed by measurements on a similar topology including non ferromagnetic copper nanowires
Dielectric behaviour of cross-linked polyethylene for HVDC cables
International audienc
Dynamic of partial discharges in cables with inner cavities during thermal and DC stresses
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Controlled growth of CoCu nanowires and application to multilayered CoCu/Cu nanowires with selected anisotropy
The effects of the solution pH and deposition potential on the structural and magnetic properties in arrays of electrodeposited CoCu nanowires with low Cu content have been studied combining ferromagnetic resonance, magnetometry and electron transmission microscopy. It is shown that, depending on the synthesis parameters, the average crystallographic structure can be controlled, giving rise to sensible changes in the effective crystal anisotropy field which varies from -4.05 to +2.75 kOe. It is also shown that in CoCu/Cu multilayered nanowires, the preferential structure of the CoCu-magnetic layer can also be controlled by both pH and deposition potential, opening an interesting route for designing multilayered CoCu/Cu nanowires with controlled and alternated crystal anisotropy
Magnetic vortices in nanowires with transverse easy axis
We present magnetotransport measurements as well as micromagnetic simulations of magnetization reversal in magnetic nanowires having strong transverse magnetocrystalline anisotropy. The interplay between exchange, demagnetizing, and magnetocrystalline energies gives rise to a micromagnetic configuration involving vortices with alternative chirality along the wire. Despite the complexity of the field angle-dependent magnetization reversal process, a very good agreement is obtained between experiments and simulations. This provides evidence that the reported magnetization process appears generally in nanowires with strong transverse magnetocrystalline anisotropy. Moreover an analytical expression is established for the angular dependency of the core switching field. The simulations indicate the occurrence of Bloch points during the core reversal