Dependence Of Soft Magnetic Properties Research Articles

The Thickness Dependence of Soft Magnetic Properties of (FeCo)-Al Alloy Thin Films

A systematic study of the film-thickness dependence of soft magnetic properties and magnetization dynamics of Fe73Co25Al2 alloy thin films has been carried out. These films have columnar structures grown along the film normal, with the average width of the columns of about 30 nm. The saturation magnetization $M_{s}$ is about 1550 emu/cc, which remains nearly unchanged with film thickness over a range from 10 to 120 nm. The coercivity $H_{c}$ is found to increase with film thickness from 15 to 64 Oe over a range of 11 to about 50 nm, and then slightly decrease with further increase of thickness. The effective damping parameter $\alpha _{\mathrm {eff}}$ measured by ferromagnetic resonance over a frequency range from 12 to 66 GHz is found to decrease with film thickness, becoming 0.0004 and 0.0006, for the films deposited onto fused silica and MgO (100) substrate, respectively.

Dependence of soft-magnetic properties on film thickness and high frequency characteristics for Fe–Co–Cr–N alloy films

Fe–Co–Cr–N thin films with various thicknesses were deposited by substrate rotation during magnetron co-sputtering. The dependence of structural and soft-magnetic properties on film thickness was investigated. It was found that all the thin films were amorphous-like and the thin films with a thickness of about 110 nm or less showed evident in-plane uniaxial magnetic anisotropy, while increasing film thickness resulted in isotropic magnetic properties. Fe–Co–Cr–N thin films with a thickness of 110 nm exhibited the most excellent soft-magnetic properties with coercivity of 4.0 Oe (318 A/m) and 2.9 Oe (230 A/m) in easy and hard axis respectively, saturation magnetization of 1.71 T (Wb/m 2) and in-plane magnetic anisotropy field of 15.5 Oe (1234 A/m). In order to further improve the high frequency characteristics of the film above, we investigated another thin film sample deposited in the same sputtering condition except that an additional static magnetic field of about 200 Oe (1.6 × 10 4 A/m) was applied to the surface of substrates.

Compositional dependence of soft magnetic properties of nanocrystalline Fe–Nb–B–P–Cu alloy tapes produced in air

The compositional dependence of the soft magnetic properties of the melt-spun Fe–Nb–B–P 1.0Cu 0.1 nanocrystalline alloy tapes with 5 mm in width has been investigated. The best magnetic properties (higher permeability than 45×10 3, lower coercivity than 5 A/m and high magnetic induction of 1.45–1.48 at 800 A/m) were obtained in a compositional range of 6.6–6.8 at% Nb and 8.4–8.8 at% B. It was confirmed that the nanocrystalline Fe 83.5–83.7Nb 6.6–6.8B 8.4–8.8P 1.0Cu 0.1 alloys also have the good productivity.

Temperature dependence of soft magnetic properties in amorphous Co 69Fe 4.5X 1.5Si 10B 15 (X=Cr, Mn, Ni) alloys

The temperature dependence of soft magnetic properties in amorphous Co 69Fe 4.5X 1.5Si 10B 15 (X=Cr, Mn, Ni) alloys was investigated by means of the changes in incremental permeability ratio (PR) as a function of temperature from 10 to 300 K. The shape of the PR curves in Co 69Fe 4.5Cr 1.5Si 10B 15 alloy does not change substantially with temperature except that the PR values become larger. The PR curve in Co 69Fe 4.5Mn 1.5Si 10B 15 alloy becomes broader and larger as temperature increases in contrast to the Co 69Fe 4.5Ni 1.5Si 10B 15 alloy in which the PR curve becomes narrower due to the decrease of anisotropy as the temperature increases.

Temperature dependence of soft magnetic properties in amorphous Co69Fe4.5Cu1.5Si10B15 alloy

The temperature dependence of soft magnetic properties in amorphous Co69Fe4.5Cu1.5Si10B15 alloy was investigated by the changes of incremental permeability ratio (PR) and magnetoimpedance ratio (MIR) as a function of temperature from 10 to 300 K. The temperature dependence of PR and MIR is directly related to the temperature dependence of soft magnetic properties. The soft magnetic properties in Co69Fe4.5Cu1.5Si10B15 alloy annealed at 400 °C are very stable for temperature variation at low temperature. The spin wave stiffness constant, D, was estimated from the temperature dependence of the magnetization at low temperature.

The role of the residual amorphous matrix in determining the temperature dependence of soft magnetic properties of nc alloys

We report here a large (300–400 K) increase of the decoupling temperature ( T c am) with increasing crystalline fraction in Nanoperm-type alloys. This is in contrast to the Finemet-type alloys where T c am varies some tens of K only around the original as-cast amorphous T c when the amorphous precursor is annealed around the first crystallization peak. H c and M r/ M s, versus T measurements have been used to monitor the exchange decoupling of the nanosized particles, because these parameters are more sensitive to decoupling than M s and μ i, which show no characteristic change at the decoupling. This enhancement of T c am has been tentatively attributed to the increasing boron content of the residual amorphous matrix whereas the zirconium atoms agglomerate in the grain boundary region.

Thickness dependence of soft magnetic properties of Fe-Si(-N) alloy films +

The thickness dependence of soft magnetic properties was investigated for Fe-Si and Fe-Si-N films. The results were compared with the predictions of Hoffmann's ripple theory. It was suggested that the optimum soft magnetic properties can be obtained for films with thickness around 2000 Å. Reducing the grain size as well as suppressing the column growth in the films lead to a way to improve the magnetic softness of Fe-based films, and the nitrogenation of the films is an effective method to realize this purpose.

Ｆｅ‐Ｃｏ‐Ｔｉ合金薄膜の磁気特性

The sputtered (Fe100-YCoY)100-XTiX (0≤X≤5, 23≤Y≤53) films were studied on the dependence of soft magnetic properties on composition, annealing temperature, and film thickness. After annealing at 823 K for 3600 s, the permeabilities of the films exhibit a maximum of 1650 at (Fe69Co31)97Ti3. The corresponding saturation magnetic flux density is 2.2 T. When the lattice constant of Fe-Co film expands by about 0.2%. the permeability reaches a maximum. When the film thickness is reached to 1357 nm, the permeability decreases to 500. The permeability of an (Fe69Co31)97Ti3/Zn0 multilayered film annealed at 773 K for 3600 s is 1100; this is about twice of the permeability of a single-layer film.

High-Frequency Permeability of Isotropic Co-Based Amorphous Films

The dependence of soft magnetic properties on the annealing conditions of Co-based amorphous films of different thicknesses was investigated in detail, in order to obtain films with a high isotropic initial permeability at high frequencies. It was found that the microscopic anisotropy of films annealed in a rotating field was increased isotropically by field-free annealing below the Curie temperature (T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> ). Thinner films with a larger microscopic anisotropy exhibited a higher isotropic permeability at high frequencies. This occurred because the natural resonance frequency is increased by increases in the microscopic anisotropy, and the influence of the eddy current on the initial permeability becomes a dominant factor at high frequencies.

等方性Ｃｏ系アモルファス膜の高周波透磁率

The dependence of soft magnetic properties on the annealing conditions for Co-based amorphous films with different thicknesses was investigated in detail, in order to obtain films having isotropically high initial permeability at high frequencies. It was found that the microscopic anisotropy of films annealed in a rotating field was increased isotropically by nonfield annealing below the Curie temperature (Tc). Thinner films having isotroplcally larger microscopic anisotropy showed isotroplcally higher initial permeability at high frequencies. This occured because the natural resonance frequency is increased by an increase in the microscopic anisotropy, and the influence of the eddy current on the initial permeability becomes a dominant factor at high frequencies.

ＭＩＧへッド用高Ｂｓ ＦｅＡｌＳｉスパッター膜

Magnetic and mechanical properties of sputtered FeA1Si films were investigated. High saturation flux density (Bs) of 14-15kG was obtained for films of 4.5-6wt%Al-5-6.5wt%Si-balance of Fe with soft magnetic properties. From the results of annealing temperature dependence of soft magnetic properties and internal stress (σ) of films, an optimum annealing temperature for superior soft magnetic properties and low σ was 600°C. There was little decrease in permeability of Mn-Zn ferrite on which the film deposited.

Magnetic properties of Fe-Ta-(b)-N films

The in-plane magnetic anisotropy and thickness dependence of soft magnetic properties for Fe-Ta-N films near the eutectic composition, annealed either in a rotating magnetic field, in a static field, or with no magnetic field, were investigated in detail. The soft magnetic films were prepared by RF reactive sputtering. The films with thicknesses greater than around 2 mu m have good soft magnetic properties. For those with thicknesses less than around 1 mu m, the soft magnetic properties deteriorate and the domain structure changes with decreasing thickness. The films annealed without magnetic field or in a rotating field have an isotropic high permeability ( mu '>or=5000 at 1 MHz) and a low anisotropy field (H/sub k/ approximately=50 A/m), whereas for the films annealed in a static field, uniaxial anisotropy is induced. This anisotropy increases with increasing N concentration. Moreover, B was added to the Fe-Ta-N system, and the relation between the structures and soft magnetic properties of Fe-Ta-B-N films was investigated. By adding B to Fe-Ta-N system, the thermal stability of soft magnetic properties is improved.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Ｆｅ‐Ｃｏ‐Ｎｂ合金薄膜の磁気特性

The dependence of soft magnetic properties on the composition and annealing temperature was studied for sputtered (Fe1-XCoX)1-YNbY (0≤X≤1.0, 0≤Y≤0.2 in weight fraction) films. The films with Y≥0.16 are amorphous while the films with 0≤X < 0.8, Y < 0.6 and 0.8≤X≤1.0, Y < 0.6 are of b.c.c. and f.c.c. structure, respectively. The lattice constant of the b.c.c. films increases with Nb content. The coercivity of the films annealed at 773 K for 3600 s exhibits a minimum of 400 A/m around Y=0.05 and X=0.3-0.8. The corresponding permeability and satuation magnetic flux density are 800 and 2 T, respectively. Coercivity depends much on the expansion of latticeconstant due to the addition of Nb and exhibits a minimum when the lattice constant of Fe-Co film is expanded 0.2%.

Ｆｅ‐Ｘ‐Ｎ（Ｘ＝Ｚｒ，Ｈｆ，Ｎｂ，Ｔａ）薄膜の磁気特性

To obtain ultra fine grains of α-Fe sputtered films of Fe-X-N (X=Zr, Hf, Nb, Ta), ternary systems in which each element X had strong affinity for nitrogen and ability of amorphous formation were prepared and the dependence of soft magnetic properties on composition of films was investigated. Good soft magnetic properties and high saturation flux density Bs were obtained in each system. In particular, Fe-Zr-N and Fe-Hf-N systems had a widespread soft magnetic region and exhibited zero magnetostriction and high Bs up to 16 kG at a certain composition.

Ｆｅ‐Ｃｏ／ＺｎＯ積層膜の軟磁気特性

The dependence of soft magnetic properties on the thickness and composition has been investigated for sputtered Fe-Co/ZnO multilayers. The coercivity decreases with the decrease in average size of crystallites D, in particular from 9 to 17 nm for all multilayers except Co/ZnO. Magnetic properties with Hc=160 A/m and μe(10 MHz)=800 are obtained for Fe/ZnO and 24Co-Fe/ZnO multilayers with D=2∼3 nm.