Ferromagnetic resonance on Ni nanowire arrays

Chipara, Mircea; Skomski, Ralph; Kirby, Roger D.; Sellmyer, David J.

doi:10.1557/jmr.2011.146

Cited by 15 publications

(6 citation statements)

References 28 publications

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“…This directly indicates that FeCo40 NWs possess a larger magnetic anisotropy. Since the values of H r for both samples are close to the saturating magnetic field in perpendicular geometry, the effective magnetic anisotropy field, H eff =H D +H MC (see equations (1) and (2)), can be determined from the following equation [17,36,37]:…”

Section: Resultsmentioning

confidence: 99%

Magnetic hardening of Fe₃₀Co₇₀nanowires

et al. 2015

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3d transition metal-based magnetic nanowires (NWs) are currently considered as potential candidates for alternative rare-earth-free alloys as novel permanent magnets. Here, we report on the magnetic hardening of Fe30Co70 nanowires in anodic aluminium oxide templates with diameters of 20 nm and 40 nm (length 6 μm and 7.5 μm, respectively) by means of magnetic pinning at the tips of the NWs. We observe that a 3-4 nm naturally formed ferrimagnetic FeCo oxide layer covering the tip of the FeCo NW increases the coercive field by 20%, indicating that domain wall nucleation starts at the tip of the magnetic NW. Ferromagnetic resonance (FMR) measurements were used to quantify the magnetic uniaxial anisotropy energy of the samples. Micromagnetic simulations support our experimental findings, showing that the increase of the coercive field can be achieved by controlling domain wall nucleation using magnetic materials with antiferromagnetic exchange coupling, i.e. antiferromagnets or ferrimagnets, as a capping layer at the nanowire tips.

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Section: Resultsmentioning

confidence: 99%

Magnetic hardening of Fe₃₀Co₇₀nanowires

et al. 2015

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“…FMR is also an informative technique to investigate the internal spin dynamics responsible for the relaxation processes in ferromagnetic nanoparticle systems. [8][9][10][11][12][13][14][15] Here, we describe the FMR studies of MgO:Ni to gain a physical insight into magnetic interactions and local anisotropy field phenomena.…”

Section: Introductionmentioning

confidence: 99%

Multi-frequency ferromagnetic resonance investigation of nickel nanocubes encapsulated in diamagnetic magnesium oxide matrix

Nellutla

Shibata

Singamaneni

et al. 2016

Journal of Applied Physics

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Partially aligned nickel nanocubes were grown epitaxially in a diamagnetic magnesium oxide (MgO:Ni) host and studied by a continuous wave ferromagnetic resonance (FMR) spectroscopy at the X-band (9.5 GHz) from ca. 117 to 458 K and then at room temperature for multiple external magnetic fields/resonant frequencies from 9.5 to 330 GHz. In contrast to conventional magnetic susceptibility studies that provided data on the bulk magnetization, the FMR spectra revealed the presence of three different types of magnetic Ni nanocubes in the sample. Specifically, three different ferromagnetic resonances were observed in the X-band spectra: a line 1 assigned to large nickel nanocubes, a line 2 corresponding to the nanocubes exhibiting saturated magnetization even at ca. 0.3 T field, and a high field line 3 (g eff $ 6.2) tentatively assigned to small nickel nanocubes likely having their hard magnetization axis aligned along or close to the direction of the external magnetic field. Based on the analysis of FMR data, the latter nanocubes possess an anisotropic

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“…where P is the AAO membrane porosity and K 2 is the secondorder term of the magnetocrystalline anisotropy energy density for uniaxial symmetry [39]. From the H r angular dependence, in the perpendicular configuration it is determined that θ M =θ H = 90°, and the H eff can be derived from the following equation [7,8,30,31]:…”

Section: Resultsmentioning

confidence: 99%

“…Understanding the origin of an enhanced coercive field in FeCo alloy NWs by Cu doping and annealing will certainly stimulate further exploration of the possibilities of magnetic hardening in 1D nanostructures. Ferromagnetic Resonance (FMR) is an effective technique to quantitatively determine the magnetic anisotropy in ferromagnetic systems, particularly in ferromagnetic NW arrays [7,8,[27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Enhanced magnetocrystalline anisotropy of Fe₃₀Co₇₀nanowires by Cu additives and annealing

et al. 2016

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The use of 3d transition metal-based magnetic nanowires (NWs) for permanent magnet applications requires large magnetocrystalline anisotropy energy (MAE), which in combination with the NWs' magnetic shape anisotropy yields magnetic hardening and an enhancement of the magnetic energy product. Here, we report on the significant increase in MAE by 125 kJ m(-3) in Fe30Co70 NWs with diameters of 20-150 nm embedded in anodic aluminum oxide templates by adding 5 at.% Cu and subsequent annealing at 900 K. Ferromagnetic resonance (FMR) reveals that this enhancement of MAE is twice as large as the enhancement of MAE in annealed, but undoped NWs. X-ray diffraction (XRD) analysis suggests that upon annealing the immiscible Cu in FeCo NWs causes a crystal reorientation with respect to the NW axis with a considerable distortion of the bcc FeCo lattice. This strain is most likely the origin of the strongly enhanced MAE.

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Ferromagnetic resonance on Ni nanowire arrays

Cited by 15 publications

References 28 publications

Magnetic hardening of Fe₃₀Co₇₀nanowires

Magnetic hardening of Fe₃₀Co₇₀nanowires

Multi-frequency ferromagnetic resonance investigation of nickel nanocubes encapsulated in diamagnetic magnesium oxide matrix

Enhanced magnetocrystalline anisotropy of Fe₃₀Co₇₀nanowires by Cu additives and annealing

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Ferromagnetic resonance on Ni nanowire arrays

Cited by 15 publications

References 28 publications

Magnetic hardening of Fe30Co70nanowires

Magnetic hardening of Fe30Co70nanowires

Multi-frequency ferromagnetic resonance investigation of nickel nanocubes encapsulated in diamagnetic magnesium oxide matrix

Enhanced magnetocrystalline anisotropy of Fe30Co70nanowires by Cu additives and annealing

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Product

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About

Magnetic hardening of Fe₃₀Co₇₀nanowires

Magnetic hardening of Fe₃₀Co₇₀nanowires

Enhanced magnetocrystalline anisotropy of Fe₃₀Co₇₀nanowires by Cu additives and annealing