Oblique-incidence anisotropy in very thin Ni-Fe films

Michijima, Masami; Hayashi, Hidetaka; Kyoho, M.; Nakabayashi, T.; Komoda, T.; Kira, T.

doi:10.1109/20.800551

Cited by 12 publications

(6 citation statements)

References 4 publications

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“…In order to achieve a high FMR frequency in the magnetic films, several experimental methods including oblique deposition, 16,17 annealing in magnetic field, 18 and interfacial exchange coupling, 19 have been often used to increase the magnetic anisotropy of thin films. For magnetic films deposited on flexible substrates, because of the effect of magnetostriction, the magnetic anisotropy can be substantially changed with the external strain produced by mechanical deformation.…”

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confidence: 99%

Static and high frequency magnetic properties of FeGa thin films deposited on convex flexible substrates

Zhan

Wei

et al. 2015

Applied Physics Letters

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Magnetostrictive FeGa thin films were deposited on the bowed flexible polyethylene terephthalate (PET) substrates, which were fixed on the convex mold. A compressive stress was induced in FeGa films when the PET substrates were shaped from convex to flat. Due to the effect of magnetostriction, FeGa films exhibit an obvious in-plane uniaxial magnetic anisotropy which could be enhanced by increasing the applied pre-strains on the substrates during growth. Consequently, the ferromagnetic resonance frequency of the films was significantly increased, but the corresponding initial permeability was decreased. Moreover, the films with pre-strains less than 0.78% exhibit a working bandwidth of microwave absorption about 2 GHz. Our investigations demonstrated a convenient method via the pre-strained substrates to tune the high frequency properties of magnetic thin films which could be applied in flexible microwave devices.

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confidence: 99%

Static and high frequency magnetic properties of FeGa thin films deposited on convex flexible substrates

Zhan

Wei

et al. 2015

Applied Physics Letters

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“…A clear anisotropic behavior in the hysteresis loops was found due to a uniaxial anisotropy induced during deposition. The uniaxial anisotropy that occurs in polycrystalline NiFe thin films has been widely reported so far, [13][14][15][16][17] and can be induced either by strain [14][15][16] FIG. 1.…”

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confidence: 99%

Dynamics of magnetization reversal in thin polycrystallineNi80Fe20films

et al. 1999

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The dynamic magnetization reversal behavior of polycrystalline Ni 80 Fe 20 films ͑thickness 60 and 200 Å͒ was studied in the temperature range 90-300 K by applying a magnetic field along the easy magnetization axis of the samples. The loop area A is found to follow the scaling relation AϰH 0 ␣ ⍀ ␤ T Ϫ␥ with ␣Ϸ0.9, ␤Ϸ0.8, and ␥ϭ0.38 for both thicknesses. This behavior is only qualitatively consistent with theoretical models if the magnetization reversal mechanism is identical for both films, independently of the applied field and sample temperature. The observed scaling exponent values indicate that domain nucleation and domain-wall motion process dominate the magnetization reversal process, which is not included in current theoretical models based on coherent rotation. Furthermore, the exponents ␣ and ␤ are found to be independent of the temperature, indicating that the dynamic reversal mechanism is unchanged in this temperature range.

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“…The physical origin of the magnetoresistance effect lies in the spin-orbit coupling: as the magnetisation M s rotates, the electron cloud about each nucleus deforms slightly, and this deformation changes the amount of scattering undergone by the conduction electrons in their passage through the lattice [10][11][12]. The amount of AMR varies for different materials, for Fe AMR ∆R/R ≈0.4%, whilst for Ni 70 Co 30 AMR ∆R/R ≈5%. The change in resistance due to AMR can be described by Eqn.…”

Section: Anisotropic Magnetoresistance (Amr)mentioning

confidence: 99%

“…films of Fe, Co, Ni, Ni 81 Fe 19 , Ni 70 Co 30 and Ni 50 Co 50 . The full and dotted lines correspond to magnetic field applied orthogonal and parallel to the current respectively in the plane of the films.…”

Section: Fig 12 Examples Of the Anisotropic Magnetoresistance Effecmentioning

confidence: 99%

“…Anisotropy fields in excess of 1500Oe were produced in 3-5nm thick polycrystalline films of Co, many times larger than the typical anisotropy of polycrystalline Co films in this thickness range, and large enough for application as a robust "pinned" film in a spin valve. It has been known for many years that the oblique deposition of magnetic materials can produce uniaxial anisotropy in magnetic films [64][65][66][67][68][69][70].…”

Section: Fig 316 Low Field Magnetoresistance Of Co-cu-co-cu-cr Spinmentioning

confidence: 99%

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In situ magnetoresistance measurements during patterning of spin valve devices

Morecroft

Prieto

Leung

et al. 2002

Journal of Applied Physics

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This dissertation describes an experimental study on the patterning of thin films and spin valve devices. Initially the change in the magnetisation reversal of ferromagnetic Ni 80 Fe 15 Mo 5 thin films was investigated as the shape anisotropy was increased using optical lithography to pattern wire arrays. These structures show a progressive increase in coercivity and a transition between single and two-stage reversal with increasing milling depth. A similar patterning technique was applied to unpinned (Ni 80 Fe 20 /Cu/Ni 80 Fe 20 ) pseudo spin valve (PSV) structures in order to enhance the coercivity of one of the ferromagnetic layers.The increased coercivity induced by micropatterning changed the natural similarity of the magnetic layers and the structure exhibited a small spin valve response. These initial measurements were carried out with separate milling and electrical characterisation steps.However, it was decided that it would be ideal to design a technique to do in-situ magnetoresistance measurements during milling. This meant that the samples could be milled and characterised in the same step, leading to a much cleaner and more efficient process. In-situ magnetoresistance measurements were carried out during micropatterning of PSV devices, and the measurements showed the evolution in the electrical response as wire structures were gradually milled through the thickness. Contrary to what was expected, the structures showed a maximum spin valve response when fully milled through. The effect of further increasing the shape anisotropy by reducing the wire width, and changing the material properties in the PSV structure has also been investigated. MR measurements were taken as the temperature was increased from 291K to 493K, and the results show that the patterned PSV structures have a better thermal stability than exchange biased spin valves with an IrMn pinning layer.The experiment was extended to the nanoscale, and the results show that a significant increase in MR is not observed despite the fact that the magnetic configuration tends more towards single domain. This is thought to be due to an increase in the initial resistance of the structures. A small increase in MR was observed as the wire width was decreased from 730 to 470nm, although the spin valve response is heavily dependent on the gallium dosage density during patterning in the Focused Ion Beam (FIB). Micromagnetic simulations were carried out, which agree with the experimental results and showed the change in the magnetisation reversal from rotation to switching as the dimensions were reduced on the nanoscale.ii Preface This dissertation is submitted for the degree of Doctor of Philosophy in the University of Cambridge. Except where specific reference is made, this is entirely my own work and includes nothing that is the outcome of work done in collaboration. No part of this thesis has been or is being submitted for any other qualification at this or any other university. This dissertation does not exceed the limit of length.Some of th...

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Oblique-incidence anisotropy in very thin Ni-Fe films

Cited by 12 publications

References 4 publications

Static and high frequency magnetic properties of FeGa thin films deposited on convex flexible substrates

Static and high frequency magnetic properties of FeGa thin films deposited on convex flexible substrates

Dynamics of magnetization reversal in thin polycrystallineNi80Fe20films

In situ magnetoresistance measurements during patterning of spin valve devices

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