Soft magnetic materials are used in integrated power magnetic devices (such as micro-inductors and micro-transformers) to achieve reasonable inductances at frequencies over a few megahertz. However, the out-of-plane (perpendicular) anisotropy, in thick films produced by vapor deposition, worsens the in-plane soft magnetic properties. This paper reports on the nano-lamination of Permalloy (Ni $_{81}$ Fe $_{19}$ ) thin films with the introduction of nitrogen-doped tantalum in between to eliminate the out-of-plane anisotropy and improve the in-plane anisotropy. This significantly improves the in-plane soft magnetic properties, reducing the coercivity from 1352 A/m to 25.5 A/m and increasing the anisotropy field from 180 A/m to 660 A/m. The high-frequency permeability was uniform up to 500 MHz, and the ferromagnetic resonance (FMR) frequency was increased to 1 GHz. These properties are ideal for high efficiency magnetic applications at high frequencies and an extended FMR frequency is imperative for gigahertz-range devices.

Enhanced In-Plane Anisotropy and Ferromagnetic Resonance Frequency in Permalloy Films Laminated With Nitrogen-Doped Tantalum

Becker-Kersten method, which involves observing hysteresis M-H loops under mechanical stress, was applied to measure magnetostriction properties in amorphous rapid quenched ribbons Fe80-xCoxP14B6. ...

Magnetostriction in Fe 80-x Co x P 14 B 6 amorphous ribbons evaluated by Becker-Kersten method

Curie temperatures and crystallization behavior of amorphous Fe81−xNixZr7B12 (x=10, 20, 30, 40, 50, 60) alloys

Using the results of electron microscopic studies of partially crystallized samples of metal glass Fe48Co32P14B6, the linear growth rate of eutectic colonies in the temperature range 679–717 K has been determined. According to these data, within the framework of the classical theory of crystallization, the effective coefficients of diffusion, which control the growth, have been calculated. The temperature dependence of the effective diffusion coefficients in Fe48Co32P14B6 glass has been found to be well approximated by an Arrhenius-type equation, and its values in the range of crystallization temperatures of glasses turned out to be approximately 2–3 orders of magnitude lower than in industrial Fe40Ni40P14B6 glass. We have determined the values of the effective diffusion coefficient and the volume density of crystallites at the onset crystallization temperature, and a correlation between preexponential factors and activation energies has been established. The parameters characterizing effective diffusion in the glass under study are shown to be in good agreement with the published data for eutectic crystallizing metallic glasses. It has been found that the physical reason for the increased thermal stability of the iron-cobalt glass structure in comparison with Fe40Ni40P14B6 is the lower mobility of atoms at the glass/crystal interface.

Effective Diffusion Coefficients and Thermal Stability of the Structure of Metallic Glass Fe 48 Co 32 P 14 B 6

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Activation Energies of Crystallization in Amorphous RMn4.5Ge4.5Fe1.5Al1.5(R = La, Y, Dy) Alloys

The Fe 41 Ni 40 Zr 7 B 12 alloy has been obtained by a melt-spinning technique in the glassy state. It revealed a narrow supercooled liquid temperature range Δn of about 16 K. The structural behaviour vs. temperature of the alloy has been examined by differential scanning calorimetry (DSC) under continuous heating (in the wide range of heating rates: 10-50 K/s). The enthalpy of crystallization AH is about 125 J/g and we have found that the change in ΔH with the heating rate is negligible and does not exceed 10%. Activation energy of crystallization was estimated by Kissinger's method to be about 296 kJ/mol for the first crystallization stage.

Structural changes in amorphous Fe41Ni40Zr7B12 alloy under heat treatment

Amorphous structure and its thermal stability as well as magnetic properties of Fe 80-x Co x P 14 B 6 (20 ≤ x ≤ 40) glasses have been studied by X-ray diffraction, non-isothermal differential scanning calorimetry (DSC) and thermomagnetic (TMG) measurements. The Curie temperature increases with Co content, while the glass transition and crystallization onset temperatures decrease. As a result, for alloys x = 30, 32 and 35 at%, the transition into paramagnetic state take place close to glass transition temperature. However, for x = 40 at% the TMG curve, in the vicinity of magnetic transition temperature, is overlapped by ferromagnetic crystallization products.

B. Idzikowski

Papers

Structural changes in amorphous Fe41Ni40Zr7B12 alloy under heat treatment

Thermal stability of amorphous structure and magnetic properties Fe80–x Cox P14B6 (x = 20–40) ribbons

Magnetic and other Properties of Heavy Rare Earth-Cobalt-Boron Amorphous Alloys

Magnetoresistance of PrxFe80−xB20 and HoxCo70−xB30 Amorphous Alloys in Magnetic Fields up to 22 T