Uniaxial Anisotropy of a Permalloy Crystal

Kaya, Seiji

doi:10.1103/revmodphys.25.49

Cited by 45 publications

(6 citation statements)

References 3 publications

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“…The phenomenon of uniaxial anisotropy in permalloy Ni 80 Fe 20 at.% (Py) films and its correlation with microstructure has attracted considerable scientific and industrial interest for decades. The proposed explanations for uniaxial anisotropy include oriented defects and oxides, 1,2 directional ordering of Fe/Ni atoms pairs, 3 shape anisotropy of an elongated ordered phase, 4 composition variation between grains 5 and more recently, localized composition non-uniformity. 6 No one of these can account for all instances of uniaxial anisotropy in the Py system, and one or more could contribute simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Effect of atomic ordering on the magnetic anisotropy of single crystal Ni80Fe20

2019

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We investigate the effect of atomic ordering on the magnetic anisotropy of Ni 80 Fe 20 at.% (Py). To this end, Py films were grown epitaxially on MgO (001) using dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS). Aside from twin boundaries observed in the latter case, both methods present high quality single crystals with cube-on-cube epitaxial relationship as verified by the polar mapping of important crystal planes. However, X-ray diffraction results indicate higher order for the dcMS deposited film towards L1 2 Ni 3 Fe superlattice. This difference can be understood by the very high deposition rate of HiPIMS during each pulse which suppresses adatom mobility and ordering. We show that the dcMS deposited film presents biaxial anisotropy while HiPIMS deposition gives well defined uniaxial anisotropy. Thus, higher order achieved in the dcMS deposition behaves as predicted by magnetocrystalline anisotropy i.e. easy axis along the [111] direction that forced in the plane along the [110] direction due to shape anisotropy. The uniaxial behaviour in HiPIMS deposited film then can be explained by pair ordering or more recent localized composition non-uniformity theories. Further, we studied magnetoresistance of the films along the [100] directions using an extended van der Pauw method. We find that the electrical resistivities of the dcMS deposited film are lower than in their HiPIMS counterparts verifying the higher order in the dcMS case.

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Section: Introductionmentioning

confidence: 99%

Effect of atomic ordering on the magnetic anisotropy of single crystal Ni80Fe20

2019

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“…In the present study we investigate the effect of angle of incidence on the structural and magnetic properties of Ni thin films deposited using dcMS and HiPIMS. We chose to work with pure Ni rather than NiFe alloys because it rejects many proposed explanations for uniaxial anisotropy based on alloying, i.e., directional ordering of Fe/Ni atom pairs [46], shape anisotropy of an elongated ordered phase [47], composition variation between grains [48] and, more recently suggested, localized composition non-uniformity [49]. Besides, we do not rotate the substrate during the deposition to simplify the conditions at the cost of losing film thickness uniformity.…”

Section: Introductionmentioning

confidence: 99%

Oblique angle deposition of nickel thin films by high-power impulse magnetron sputtering

Hajihoseini¹,

Kateb²,

Ingvarsson³

et al. 2019

Beilstein J. Nanotechnol.

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Background: Oblique angle deposition is known for yielding the growth of columnar grains that are tilted in the direction of the deposition flux. Using this technique combined with high-power impulse magnetron sputtering (HiPIMS) can induce unique properties in ferromagnetic thin films. Earlier we have explored the properties of polycrystalline and epitaxially deposited permalloy thin films deposited under 35° tilt using HiPIMS and compared it with films deposited by dc magnetron sputtering (dcMS). The films prepared by HiPIMS present lower anisotropy and coercivity fields than films deposited with dcMS. For the epitaxial films dcMS deposition gives biaxial anisotropy while HiPIMS deposition gives a well-defined uniaxial anisotropy. Results: We report on the deposition of 50 nm polycrystalline nickel thin films by dcMS and HiPIMS while the tilt angle with respect to the substrate normal is varied from 0° to 70°. The HiPIMS-deposited films are always denser, with a smoother surface and are magnetically softer than the dcMS-deposited films under the same deposition conditions. The obliquely deposited HiPIMS films are significantly more uniform in terms of thickness. Cross-sectional SEM images reveal that the dcMS-deposited film under 70° tilt angle consists of well-defined inclined nanocolumnar grains while grains of HiPIMS-deposited films are smaller and less tilted. Both deposition methods result in in-plane isotropic magnetic behavior at small tilt angles while larger tilt angles result in uniaxial magnetic anisotropy. The transition tilt angle varies with deposition method and is measured around 35° for dcMS and 60° for HiPIMS. Conclusion: Due to the high discharge current and high ionized flux fraction, the HiPIMS process can suppress the inclined columnar growth induced by oblique angle deposition. Thus, the ferromagnetic thin films obliquely deposited by HiPIMS deposition exhibit different magnetic properties than dcMS-deposited films. The results demonstrate the potential of the HiPIMS process to tailor the material properties for some important technological applications in addition to the ability to fill high aspect ratio trenches and coating on cutting tools with complex geometries.

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“…Simulation parameters for this study reported here are as follows: We have used permalloy (Py) (78.5% nickel, 21.5% iron composition) magnetic dots which is a pronounced polycrystalline soft magnetic material with uniaxial anisotropy constant value set as zero (i.e. low coercive field) and larger exchange energy comparatively to the magnetocrystalline anisotropy energy (MAE) [52,53]. In lieu of time, the maximum torque |m×h| set to 10 −5 A m −1 , with damping coefficient of 0.25, saturation magnetization of 800×10 3 A m −1 and the exchange stiffness constant of 13×10 −12 J m −1 [30].…”

Section: Additional Informationmentioning

confidence: 99%

Nanomagnetic logic based runtime Reconfigurable area efficient and high speed adder design methodology

Sivasubramani¹,

Mattela²,

Rangesh³

et al. 2020

Nanotechnology

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In this study, we present a runtime reconfigurable nanomagnetic (RRN) adder design offering significant area efficiency and high speed operations. Subsequently, it is implemented using a micromagnetic simulation tool, by exploiting the reversal magnetization and energy minimization nature of the nanomagnets. We compute the carry and sum of the 1-bit full adder using only two majority gates comprising a total of 7 nanomagnets and single design layout. Consequently, the on-chip clocking schematic for the proposed RRN adder implementation for both horizontal and vertical layouts are introduced. The quantitative analysis of the required resources for higher bit adder architecture using the proposed design is performed and compared with state-of-the art. The proposed design methodology leads to ∼86%, ∼83% and ∼93% reduction in the number of nanomagnets, majority gates and clock cycles respectively resulting in an area efficient and high speed RRN adder architecture.

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Uniaxial Anisotropy of a Permalloy Crystal

Cited by 45 publications

References 3 publications

Effect of atomic ordering on the magnetic anisotropy of single crystal Ni80Fe20

Effect of atomic ordering on the magnetic anisotropy of single crystal Ni80Fe20

Oblique angle deposition of nickel thin films by high-power impulse magnetron sputtering

Nanomagnetic logic based runtime Reconfigurable area efficient and high speed adder design methodology

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