Magnetic Properties Of Permalloy Research Articles

Anisotropic properties of oblique angle deposited permalloy thin films

The structural, transport, and magnetic properties of permalloy (Ni81Fe19) thin films prepared by oblique angle deposition have been investigated. With the increasing oblique angle, column-like microstructures developed on the films while their porosity augmented. Due to the unique columnar microstructures, a deposition-angle-dependent uniaxial anisotropy was induced in the films. While the normally deposited film was electrically isotropic, the films grown at non-zero angles showed enhanced anisotropic conduction. The magnetization data showed that for the films deposited at angles < 70° the easy magnetization axis was along the films in-plane direction and perpendicular to the incident flux direction. As the oblique angle exceeded 70° the magnetization easy-axis reoriented along the long-columnar axis. The systematic increase of oblique angle triggered a noticeable enhancement in the coercivity , especially for the extreme oblique angles (α > 70°). The experimental results demonstrated that oblique angle deposition, particularly at angles > 70°, can substantially transform the electro-magnetic properties of thin films.

Additive manufacturing of soft magnetic permalloy from Fe and Ni powders: Control of magnetic anisotropy

Abstract The influence of the process parameters in Laser Beam Melting (LBM) on the element distribution and magnetic properties of permalloy ( Ni 78.5 Fe 21.5 ) is studied. Iron and nickel powders are mixed in the respective proportions to build twenty-five permalloy samples. The process parameters for each sample are varied to achieve different volume energy densities. An increase of the saturation magnetization MS up to 14% of the samples with respect to the initial powder blend is found. For a volume energy density of 428 J mm 3 we detect a stripe-like segregation of iron and nickel in the uppermost layer. In the volume a homogeneous element distribution is found. The segregation at the surface leads to a sizable uniaxial magnetic anisotropy. When using parameter combinations resulting in similar volume energy densities, we observe different surface morphologies depending on scan speed and laser power. The implications for creating tailored magnetic anisotropy directions in Fe-Ni soft magnets are discussed.

Effect of Ta Underlayer on Thickness-Dependent Magnetic Properties of Ni–Fe Films

We report the effect of Ta underlayer on the structural and the magnetic properties of Permalloy (Ni81Fe19) thin films over a wide range of film thicknesses ( t Ni–Fe = 10–200 nm). For this purpose, Ta (5 nm)/Ni–Fe ( t Ni–Fe nm)/Ta (2 nm) films were grown on thermally oxidized Si substrates under the presence and the absence of biasing magnetic field (1000 Oe). The Ni–Fe films grown under the presence and the absence of biasing magnetic fields are referred to Ta/Ni–Fe(M) and Ta/Ni–Fe(NM), respectively. X-ray diffraction studies revealed that the Ta underlayer plays an important role in the formation of fcc-(111) Ni–Fe texture in both the Ta/Ni–Fe(M) and Ta/Ni–Fe(NM) films. In addition, the values of average crystallite size depend on the film thickness, biasing field, and Ta underlayer. Thickness-dependent magnetic hysteresis ( M–H ) loops demonstrate a strong in-plane uniaxial anisotropy in both the Ta/Ni–Fe(NM) and Ta/Ni–Fe(M) films. The uniaxial anisotropy constant ( Ku ) depends not only on the film thickness, but also strongly on the biasing magnetic field. Coercivity decreases with increasing film thickness for both the Ta/Ni–Fe(NM) and Ta/Ni–Fe(M) films, and approaches to a minimum of $\sim$ 0.4 Oe even at t Ni–Fe = 200 nm. Furthermore, the observed magnetic domain patterns of Ni–Fe films show their dependence on the Ta underlayer, biasing field, and Ni–Fe thickness. The effects of the Ta underlayer, the Ni–Fe film thickness, and the biasing-field driven uniaxial anisotropy on the structural and the magnetic properties are discussed on the basis of reduction in strain at the Ta/Ni–Fe interface.

Examination of Precise Measurement of DC Magnetic Properties of Permalloy Under Low Flux Density More Than a Few mT

Permalloy is used in a magnetically shielded room to inhibit the penetration of external magnetic field, etc. The flux density in permalloy used in the shielded room is of the order of a few mT or lower. In order to examine the performance of such a shielded room, the dc magnetic properties at low flux density is necessary. In this paper, we developed a measurement method of dc (5 mHz) magnetic properties of permalloy under such a low flux density. It is shown that the dc magnetic properties could be measured more than 4 mT by paying the attention to the degaussing of specimen and applying the correction of drift and offset of measurement system.

Impact of Metal-Organic Interface on the Growth Mechanism and Magnetic Properties of Permalloy (Fe : Ni) Films Sputtered on Self-Assembled Monolayers of Polar and Nonpolar Molecules

Metal deposition on self-assembled monolayers (SAMs) with different terminal organic functional groups is a growing area of research and the metal-organic interface has been extensively studied in the past two decades. Apart from impacting existing technologies, it may have a profound impact on the emerging future technologies such as molecular electronics. The morphology of the deposited metals is strongly influenced by the nature of the chemical interactions occurring at the interface of the organic functional group (OFG) of the SAM and the deposited metal. Our interest for such studies stems from different perspective, as we are interested in determining the impact of the interface on the morphology and hence the magnetic properties of the deposited magnetic materials. We have sputtered a magnetic material, permalloy (Ni79Fe21), on self-assembled monolayers of polar and nonpolar molecules, and have observed contrasting magnetic behaviors of permalloy on these surfaces. We have observed the formation of uniform film on polar regions and cluster are formed on nonpolar regions. Further investigations reveal that the cluster formation gives rise to superparamagnetism, while the uniform film shows a usual ferromagnetic behavior. The observed contrast in morphology and magnetism of Py is attributed to different growth mechanisms arising from difference in polarity of the SAM surfaces.

Study of thickness variation, morphology, and magnetic properties of Permalloy on organic monolayers

We have sputtered different thicknesses of Permalloy (Ni79Fe21) on self-assembled monolayers (SAMs) with polar (–COOH) and nonpolar (–CH3) organic functional groups and have observed interesting changes in morphology and magnetic properties. At very low thicknesses (∼1.5–3 nm) the morphology and magnetic properties of the deposited Permalloy are similar to those observed for isolated superparamagnetic clusters on both types of SAM surface. Further increase in the deposition (∼4 nm and above) of Permalloy results in a ferromagnetic film formation on the polar SAM, and superparamagnetic cluster formation remains apparent on the nonpolar SAM up to a thickness of 8 nm. The polarity of the organic underlayer plays a critical role in this regime. At higher thicknesses (∼12 nm and above) Permalloy exhibits usual ferromagnetic behavior on both types of SAM surfaces.

粉末射出成形（ＰＩＭ） ＭＩＭプロセスにおけるＦｅ‐５０ｍａｓｓ％Ｎｉの磁気特性改善

Metal injection molding(MIM)process is hoped to be one of processing for required to more complicated parts of magnetic components.In this study, the effect of different types of powders(prealloyed and mixed elemental powders)on the magnetic properties of permalloy(Fe-50mass%Ni)through the MIM technique was investigated. Approximately 94% of theoretical density was obtained by using the prealloyed powder, and the retained carbon and oxygen contents were controlled to be low. On the other hand, 96% of theoretical density was obtained by using the mixed elemental powder, but the magnetic properties were inferior to that of prealloyed powder's because of high retaind oxygen content. By using the carbonyl Fe powder with high carbon, the retained oxygen and carbon content could be controlled to be low, resulting in the improved magnetic properties.

Effect of CoPtCr/Cr on the magnetic properties of Permalloy

The effect of a hard bias material, CoCrPt, on the magnetic properties of Permalloy has been studied as a function of spacer layer thickness. In particular, a large increase in the coercivity without reduction in squareness of NiFe is observed. This increase may have relevant implications in the design of magnetoresistive heads. The results are explained qualitatively using a Random Field approach in the Imry-Ma.

Interdiffusion in titanium permalloy thin films

This paper presents the results of investigation of interdiffusion in titanium permalloy thin film. It is found that interdiffusion in titanium-permalloy thin films is very detrimental to the magnetic properties of permalloy. Severe interdiffusion can take place with composite Ti/NiFe film annealed at 250°C for 90 minutes. Auger Analysis indicates the diffusion mechanism involves mainly Ni loss from the permalloy layer and diffusion into the Ti layer. Atmospheric exposure of the Ti layer before NiFe deposition can effectively control the interdiffusion process and prevent loss of magnetoresistive response. The x-ray diffraction data has indicated the formation of a Ni-Ti alloy to which may be attributed the degradation of the magnetic properties of Permalloy.

Coercive force of electrodeposited NiFe on top of conductors for SLM bubble device applications

Reduction of the bubble size in bubble devices made evident that the permalloy used in the structure has to comply with very strict specifications of coereivity and remanence. This paper reports on a study aimed at minimizing the Hc of permalloy electroplated on top of thick gold conductor, such as is used in the SLM, conductor first, devices. The coercive force of electroplated permalloy was studied as a function of the type of the underlying metal conductor, its thickness, and its surface characteristics as determined by the type and rate of deposition. Also studied were the correlation between Hc and the electroplated permalloy thickness, and the effect of annealing on the coercive force. It was found that reproducibly the best magnetic properties of permalloy are obtained when a thin layer of permalloy is evaporated on the gold conductor prior to electrodeposition of the permalloy structure.

Effect of Tension Upon Magnetization and Magnetic Hysteresis in Permalloy

Magnetic properties of permalloy.---Effect of tension on magnetization and hysteresis. Wires of 5 nickel-iron alloys containing 45, 65, 78.5, 81 and 84 percent Ni, 60 cm long and 0.1 cm in diameter, were studied by a ballistic method, for tensions up to 10,000 lb per ${\mathrm{in}.}^{2}$ and fields up to saturation (10 to 20 gauss). Permalloy with 81 percent Ni is nearly indifferent to tension in its magnetic behavior; permalloy with less nickel is more easily magnetized and has less hysteresis when under tension, while 84 percent permalloy is more difficulty magnetized and has greater hysteresis when under tension. The saturation values are independent of the tension. In 78.5 percent permalloy, under a tension of 3560 lb per ${\mathrm{in}.}^{2}$, saturation is reached at only 2 gauss (and is practically complete at 0.2 gauss) and the hysteresis loss is only 80 ergs per ${\mathrm{cm}}^{3}$ per cycle, so small that it may be regarded as due to slight inhomogeneity rather than to any essential features of the magnetization process. Relation to crystal orientation. X-ray examination proves that this abnormally low loss is not due to any peculiar orientation of the crystal axes as the crystals are found to be oriented at random. Magnetostriction behavior can be deduced from these results. Above 81 percent Ni, permalloy contracts like Ni while below 81 percent Ni, permalloy expands like Fe.Demagnetising factor for a wire with a length 600 times the diameter, was determined experimentally and found to vary from a maximum of 1.6\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ to a low value, the changes being like these previously described by Benedicks for iron.