Films Of Magnetic Materials Research Articles

Effects of the pH Value on the Electrodeposition of Fe–P Alloy as a Magnetic Film Material

The effects of the pH value on the electrodeposition process of Fe–P alloys from a ferrous sulfate bath with sodium hypophosphite as the phosphorus source are investigated. The composition, structure, and magnetic properties are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, and vibrating sample magnetometry. As the pH value is varied from 1.2 to 2.4, the P content of the alloys gradually decreases from 11.42 to 3.34 wt % while the structure changes from amorphous to a polycrystalline structure. Electrochemical analyses indicate that the electrochemical reduction of Fe2+ ions and H2PO2– ions proceeds independently in solution with a pH value lower than 1.5, while it simultaneously proceeds in solution with a pH value higher than 2. Density functional theory calculations and molecular dynamics simulations reveal that Fe2+ ions and H2PO2– ions coordinate together to form a contact ion pair [nFe·m(H2PO2)]2n−m in weak acidic solution and thereafter a coelectrodeposition process of Fe atoms and P atoms takes place on the surface of the cathode. On the contrary, Fe2+ ions inside the solvation shell of H2PO2– ions in strong acidic solution are replaced by H3O+ ions, resulting in Fe2+ ions and H2PO2– ions being independently electrodepositing on the surface of the cathode. The diffusion of [nFe·m(H2PO2)]2n−m ion pairs is much difficult than that of H2PO2– ions coordinated with H3O+. The adsorption of [nFe·m(H2PO2)]2n−m ion pairs on the surface of the electrode is also weaker than that of H2PO2– ions. All of these make the P content in electrodeposited Fe–P alloys higher in strong acidic solutions than that in weak acidic solutions. The increase in the P content obviously inhibits the grain growth, resulting in the structure gradually transforming from polycrystalline to amorphous. A mechanism about the effect of pH values on the electrodeposition process of Fe–P alloys is proposed.

Modeling the Distribution of Magnetization in a Rectangular Strip with an Axis of Easy Magnetization Perpendicular to the Plane

A theory is constructed for the ordering of magnetic domains in magnetic film materials in the presence of point dipole magnetic inhomogeneities. The distribution of magnetization is modeled for a rectangular strip with an axis of easy magnetization perpendicular to its plane in the presence of point dipole magnetic inhomogeneities. 3D modeling of the magnetic structure of the plate reveals the curvature of the domain boundary caused by the field of local magnetic inhomogeneity and along the thickness of the plate.

Curving of a Domain Boundary in the Presence of an Inclined Symmetrical Magnetic Inhomogeneity in Film Materials with High Anisotropy

The theory of magnetic domain ordering in magnetic film materials when there is an inclined and symmetrically located magnetic inhomogeneity in the strip domain is developed, allowing for variation in both the magnetostatic energy and the energy of anisotropy of the curved domain boundary.

Sealing Performance Evaluation Method of Nano-scale Magnetic Thin Film Materials in Marine Tanks

Wang, S.; Jiang, J., and Cao, W., 2019. Sealing performance evaluation method of nano-scale magnetic thin film materials in marine tanks. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 941–946. Coconut Creek (Florida), ISSN 0749-0208.In order to evaluate the sealing performance of nano-scale magnetic thin film materials in marine tanks, a method for evaluating the sealing performance of nano-scale magnetic thin film materials in marine tanks based on spatial visual image feature extraction is proposed. The differential frame point scanning and spatial vision high resolution imaging analysis method are used to collect the image information of ship tank nano-scale magnetic thin film material. The sealing gap of ship tank nano-scale magnetic film material, the weakening of material mechanics, the sealing frame point and other parts of the three-dimensional frame structure reconstitute image modeling. The edge structure feature decomposition and texture segmentation of ship tank nanoscale magnetic film material images are carried out. The stress fitting model of structural seal gap of ship tank nano-scale magnetic film material is constructed. The feature point extraction and mechanical state dynamic estimation of ship tank nano-scale magnetic film material seal gap are carried out by using three-dimensional frame structure reconstruction image feature extraction method, and the accurate prediction and evaluation of seal gap state of ship tank nano-scale magnetic film material seal are realized. The simulation results show that the sealing performance of nano-scale magnetic thin film material in ship tank is tested by this method, and the positioning accuracy of sealing gap point of nano-scale magnetic thin film material in ship tank is higher, the reliability index of closed performance evaluation is better, and the failure probability is the smallest.

Fabrication and magnetic properties of strip-patterned FeCoB-SiO2 nanoparticle films for GHz application

A series of high stacking density FeCoB-SiO2 nanoparticle films with strip structures were prepared by electric field-assisted deposition technique attached by thermal oxidization processing. We obtained the expected soft magnetic properties for strip-patterned FeCoB-SiO2 nanoparticle films. In this situation, relatively large permeability and high ferromagnetic resonance frequency are easily achieved in a wide gigahertz range. More importantly, the great GHz electromagnetic performance can be maintained in a wide SiO2 volume fraction range by carefully controlling the width of SiO2 strips. These results show that this kind of film materials have great potential for application in integrated devices operated in the gigahertz frequency range. Meanwhile, these single layer soft magnetic film materials with high permeability in the GHz range and high resistivity are easily merged into the micro manufacturing technology, such as CMOS and MEMS technique.

Features of a Domain Structure with Asymmetric Magnetic Heterogeneity in Film Materials with High Anisotropy

The theory of magnetic domain ordering in magnetic film materials with asymmetric magnetic heterogeneity is considered, with allowance for changes in the magnetostatic energy and that of the anisotropy of a curved domain boundary. The effect the parameters that determine changes in the energy of the magnetostatic interaction of the domain structure and the energy of the anisotropy of the curved domain boundary have on the shape and value of domain boundary bending is analyzed.

Break the Acher's limit: Improve both resonance frequency and initial permeability in patterned FeNi strip film

The development of soft magnetic film materials gradually tends to pursue the higher resonance frequency which is beneficial to set the maximum operation speeds and lager permeability to make devices miniaturization. The studies on improving frequency have been widely reported. However, being restricted by the traditional Acher's limit, the research of simultaneously obtaining larger initial permeability and keeping higher frequency is still challenging. In this paper, the lamella-like (LL) magnetic strips with two types of line-widths are designed to align according to varied combined periods to form parallel shish-kebab-like structures (SKL). As the coercivity and remanence enhance, the outstanding in-plane uniaxial magnetic anisotropy is also investigated from 150 to 90 Oe when the unsymmetrical dipolar interaction is induced between two combined strips. In addition, the resonance frequency increases from 2.84 to 7 GHz and still sustains the same value after being assembled with the different periodic units. Meanwhile, the initial permeability also keeps a higher value around 85 compared to the value of 15 before combination, which breaks through the Acher's limit. Therefore the method of tunable magnetic properties by introducing the shape factor and dipolar interaction together has a great potential research value in high-frequency soft magnetic film fields.

Accurate Estimation of $c$-Axis Distribution and Order Degree of $L1_0$ Crystal in Magnetic Thin Film

The c-axis distribution and the accurate order degree of magnetic thin film with L10 structure are investigated by using a combination of out-of-plane and in-plane X-ray diffractions (XRDs). An L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> film formed on (001)-oriented underlayer or substrate includes a crystal of (001) orientation with the c-axis normal to the film surface and/or a crystal of (100) orientation with the c-axis lying in the film plane. An appearance of L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> superlattice reflection in either out-of-plane or in-plane XRD indicates a formation of L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (001) or L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (100) crystal. Accurate L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> order degrees of (001) and (100) crystals are calculated from the respective XRD data for FePt and FePd films. An accurate order degree of film total is estimated by taking into account the volume ratios of two types of L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> crystal. A simplified method for estimating order degree, where there are only two kinds of parameter, intensities of (001) and (002) reflections and lattice constant of c, is also proposed for typical L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> magnetic film materials of FePt, CoPt, FePd, MnAl, FeNi, FeAu, and FeRh. The order degree estimated by simplified method agrees with the accurate value within a small error of less than a few percentages.

ChemInform Abstract: Recent Development of Thin Film Materials for Magnetic Heads

Recent developments of soft magnetic film materials in the past decade are reviewed. Approximately 20 kinds of alloy systems with high saturation induction of more than 10 kG have been reported in the last decade, although there were only three conventional head materials: Mn-Zn ferrite, Permalloy, and Sendust. A particular focus of the review is nanocrystalline films and multilayer films. Also reviewed are improvements in single-layer homogeneous films of Fe, Fe-Si, Sendust, and Fe/sub 16/N/sub 2/. Almost all the materials reported are Fe-based alloys, and some alloys are nitrogen related: iron-nitride compounds or nitrogen-containing alpha -Fe or Sendust. >

A new generation of CMOS-compatible high frequency micro-inductors with ferromagnetic cores: Theory, fabrication and characterisation

A new generation of CMOS-compatible micro-inductor prototypes with magnetic cores were realized, characterised as well as theoretically modelled in a frequency range up to 4 GHz, a frequency range where, e.g., mobile communication and global positioning systems (GPS) are operated. The micro-inductor's electrical magnitudes like inductance ( L) and quality factor ( Q) were theoretically described by means of an equivalent circuit model taking the frequency behaviour of the magnetic film core, expressed by the Landau-Lifschitz and Maxwell equations, into account. Six inch targets were used to deposit metallic layers (Al 99Si 0.5Cu 0.5), diffusion barriers (Si 3N 4), insulating layers (SiO 2) and magnetic films (Fe 39Co 30Ta 8N 23) by DC or reactive r.-f.-magnetron sputtering. All film materials were patterned by NUV-lithography (Near Ultra Violet), plasma beam milling and reactive ion etching to form the micro-inductors on 4-inch silicon wafers. The inductor windings are arranged in a way that they possess a low resistance and generate a quasi closed flux at the end of the cores to minimise eddy current losses in the silicon substrate. In order to diminish demagnetising effects in an efficient working core the magnetic films were patterned into micro squares with lateral dimensions of 20 and 100 μm with 100 nm in thickness. More magnetic volume and a higher micro-inductor cross-section was achieved by producing 100 nm magnetic double layers separated by a 800 nm thick Si 3N 4 inter-layer. To guarantee a sufficiently high cut-off frequency of the magnetic films, they were annealed in a static magnetic field at a temperature of 400 °C for uniaxial anisotropy induction. This represents a temperature treatment where aluminium CMOS processes take place. As a result of patterning, the magnetic film material exhibited a remarkable increase of the cut-off frequency from 2 GHz in laterally extended films up to 3.2 GHz which could be also observed in the measured frequency dependent inductance and quality factor. This was accompanied by an acceptable decrease of the initial permeability that still enabled initial inductances between 1 and 2 nH to be attained.

Internal oscillations of solitons in ferromagnets on a cylinder in an axial magnetic field

Analysis of the small amplitude oscillations around the structure of solitons in ferromagnets on a cylinder in an external axial magnetic field shows the presence of a localized mode. The local mode has a well-defined frequency determined by the strength of the magnetic field and by the cylinder radius. It may be possible to observe this mode through resonance experiments for cylindrically wrapped thin films of magnetic materials with a finite density of solitons.

Quantized Topological Solitons in Antiferromagnets on an Infinite Cylinder

We semiclassically quantize static topological solitons which exist within a continuum Heisenberg model of an antiferromagnet on an infinite rigid cylinder. It is shown that the energy of a quantized fundamental soliton and the spin-wave spectrum are strongly dependent on the geometry of isotropic spin systems. This dependence implies that the spin-wave gap increases and the energy of a quantized soliton decreases as the radius of the cylinder decreases. Our calculations may have relevance for the recently synthesized carbon nanotubes or cylindrically wrapped thin films of magnetic materials with antiferromagnetic order.

The Magentic Susceptibility in Ultrathin Films of Magnetic Materials

ABSTRACTIn this paper we have studied the dia and paramagentic susceptibilities of the holes in ultrathin films of magnetic materials in the presence of a parallel magentic field on the basis of a newly derived dispersion law for such systems. The numerical computations are performed taking Hg1-xMnx Te and Cd1-xMnx Se as examples. Both the susceptibilities increses with decreasing doping and film thickness respectively. It is important to note that not only the paramagnetic-to-diamagnetic susceptibility ratio for the present case deviates from (1/3) in conventional semiconductors, but also that is a critical region, where quenching of the diamagnetic occurs. The theoretical analysis is in agreement with the experimental datas as given elsewhere.

Permeability of microstrip thin films of various materials

Soft magnetic bilayered microstrip films have been studied for various materials such as Ni–Fe–Mo–Cu, Co–Zr–Mo–Ni, Fe–Si–N, and Ni–Fe in terms of their magnetization dynamics. Effects of the strip width and the interlayer thickness on permeability were investigated. An optimum interlayer thickness was found for obtaining the maximum permeability for those films except Fe–Si–N, but the optimum value differs in magnetic film material. A scanning Kerr effect microscope observation reveals that permeability variations with strip width related to changes of the dynamic domain configurations of the strips. All magnetic film materials except Fe–Si–N show a high permeability of more than 1000 at 2 μm strip width at each optimum interlayer thickness. When the film width is reduced to 1 μm, however, the permeability decreases significantly regardless of the interlayer thickness and kinds of the film materials. For such narrow strip film, a higher permeability is obtained for higher anisotropy field. It is concluded that the shape anisotropy of the micropatterned films must be controlled for achieving a higher permeability.

Soft magnetic properties of evaporated Fe-Al-Ti alloy films

Fe-Al-Ti alloy films were prepared at 673 K by an electron-beam evaporation method. Excellent soft magnetic properties (a permeability of about 2000 at 5 MHz and a magnetization of about 1.9 T) were obtained. It is suggested that it is possible to develop soft magnetic film materials with high saturation magnetization, high permeability and small magnetostriction in and Fe-Al alloy system.

Recent development of thin film materials for magnetic heads

Recent developments of soft magnetic film materials in the past decade are reviewed. Approximately 20 kinds of alloy systems with high saturation induction of more than 10 kG have been reported in the last decade, although there were only three conventional head materials: Mn-Zn ferrite, Permalloy, and Sendust. A particular focus of the review is nanocrystalline films and multilayer films. Also reviewed are improvements in single-layer homogeneous films of Fe, Fe-Si, Sendust, and Fe/sub 16/N/sub 2/. Almost all the materials reported are Fe-based alloys, and some alloys are nitrogen related: iron-nitride compounds or nitrogen-containing alpha -Fe or Sendust.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Thermal expansion of lattice parameters of some rare earth gallium garnets and magnetic bubble domain materials

The rare earth gallium garnets Dy <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> , Gd <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> , Sm <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> , and Nd <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> used as substrate materials and the magnetic film materials EuEr <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5-x</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0 \leq x \leq 5</tex> ) and Eu <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Er <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3-x</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.7</inf> Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4.3</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0 \leq x \leq 3</tex> ) have been prepared and their lattice parameters measured between room temperature and 1200°C. In the series R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> , the room temperature lattice constant decreases linearly in the order Nd>Sm>Gd>Dy. The curve <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Deltaa/a_{0}</tex> (a <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> = lattice constant at 25°C, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Deltaa</tex> = lattice constant - a <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> versus <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</tex> shows a very slight concavity over the whole temperature interval with higher values of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Deltaa/a_{0}</tex> in the same order as the room temperature lattice constants. The lattice constants follow Vegard's law with the substitution of europium for erbium in the series Eu <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Er <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3-x</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.7</inf> Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4.3</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> and decrease with decreasing europium content. The curves of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Deltaa/a_{0}</tex> have the same shape as the rare earth gallium garnets, but with higher values of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Deltaa/a_{0}</tex> in the opposite order to the room temperature lattice constants. Substitution of gallium for iron in the series EuEr <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5-x</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> caused positive deviation from Vegard's law and a decrease in the room temperature lattice constants. The values of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Deltaa/a_{0}</tex> increase with increasing iron content. The implications of these observations on the properties of magnetic films for bubble domain applications are discussed.

Magnetic film materials

Magnetic films are used in the information processing area in two principal applications: random access high speed memory and serial access lower speed memory. The application requirements for magnetic films of these two types, the material properties needed to meet these requirements, and the metallurgical structures which give rise to the properties are described. The directions of present development work and of possible future improvements in the technology are discussed.