Magnetization reversal process and nonlinear magneto-impedance in Cu/NiFe and Nb/NiFe composite wires

The magnetization reversal of Cu/NiFe and Nb/NiFe composite wires carrying AC current is studied. The frequency spectrum of a voltage induced in a pick-up coil wound around the wire is analyzed. The frequency spectrum is shown to consist of even harmonics within a wide range of AC current amplitudes and longitudinal DC magnetic fields. The strong dependencies of the harmonic amplitudes on the DC field are found. The results obtained may be of importance for the design of weak magnetic field sensors.Comment: 8 pages, 4 figures, publishe

High frequency magnetic permeability of nanocomposite film

The high frequency magnetic permeability of nanocomposite film consisting of the single-domain spherical ferromagnetic particles in the dielectric matrix is studied. The permeability is assumed to be determined by rotation of the ferromagnetic inclusion magnetic moments around equilibrium direction in AC magnetic field. The composite is modeled by a cubic array of ferromagnetic particles. The magnetic permeability tensor is calculated by solving the Landau-Lifshits-Gilbert equation accounting for the dipole interaction of magnetic particles. The permeability tensor components are found as functions of the frequency, temperature, ferromagnetic inclusions density and magnetic anisotropy. The obtained results show that nanocomposite films could have rather high value of magnetic permeability in the microwave range

A generalization of Snoek's law to ferromagnetic films and composites

The present paper establishes characteristics of the relative magnetic permeability spectrum $\mu$(f) of magnetic materials at microwave frequencies. The integral of the imaginary part of $\mu$(f) multiplied with the frequency f gives remarkable properties. A generalisation of Snoek's law consists in this quantity being bounded by the square of the saturation magnetization multiplied with a constant. While previous results have been obtained in the case of non-conductive materials, this work is a generalization to ferromagnetic materials and ferromagnetic-based composites with significant skin effect. The influence of truncating the summation to finite upper frequencies is investigated, and estimates associated to the finite summation are provided. It is established that, in practice, the integral does not depend on the damping model under consideration. Numerical experiments are performed in the exactly solvable case of ferromagnetic thin films with uniform magnetization, and these numerical experiments are found to confirm our theoretical results. Microwave permeability measurements on soft amorphous films are reported. The relation between the integral and the saturation magnetization is verified experimentally, and some practical applications of the theoretical results are introduced. The integral can be used to determine the average magnetization orientation in materials with complex configurations of the magnetization, and furthermore to demonstrate the accuracy of microwave measurement systems. For certain applications, such as electromagnetic compatibility or radar absorbing materials, the relations established herein provide useful indications for the design of efficient materials, and simple figures of merit to compare the properties measured on various materials

The effect of stripe domain structure on dynamic permeability of thin ferromagnetic films with out-of-plane uniaxial anisotropy

The permeability is calculated for a thin ferromagnetic film with the stripe domain structure and out-of-plane uniaxial magnetic anisotropy. Analytical expressions for the frequency dependence of components of permeability tensor are derived with the use of the Smit-Beljers method, with the thickness of domain walls and the domain wall motion being neglected. The effect of the domain width and the angle between the anisotropy axis and the film plane on the frequency dependence of the permeability is analyzed. General equations relating the static permeability components and the ferromagnetic resonance frequencies are found. The results of the approach are applied to the derivation of the constraint for the microwave permeability of thin ferromagnetic films. The analysis of the constraint as a function of the axis deviation angle, the domain aspect ratio and the damping parameter allows the conditions to be found for maximal microwave permeability. The results obtained may be useful in connection with the problem of developing high-permeable microwave magnetic materials.Comment: 22 pages, 6 figure

CHEMICAL BONDS DISSOCIATION ENERGY

In previous publications dealing with experimental mass spectrometry of tungsten hexacarbonyl, hexafluoroacetylacetone and its bidentate metal complexes M(hfac)2; M = Cu, Pd the obtained data have been not adequately systematized. In this paper, we analyze the previously published experimental data of the various bond dissociation energy. A modified Yukawa potential, which is the exact solution of the problem dependence the chemical bond energy of its length, is used to analyze the experimental data. Experimental results of the formation of ions can be interpreted only in terms of the formation of fractionally charged quasi-particles. As an experimental technique, mass spectrometry of negative ions in electron resonance capture mode ranks next to the fractional quantum Hall effect in which fractional values of the charge quantization are observed. Also noted the possibility capture of electron with “negative” kinetic energy.</p

Absolute value of bond dissociation energy as a reaction direction marker.

The calculation problem of bond-dissociation energy D0(M+-S) for M = Sc, Ti, V, Y, Zr, Nb was solved using the fundamental law of nature determining the dependence of chemical bond dissociation energy on its length. The recommended experimental values from literature are as follows D0(Sc+-S)=4.97±0.05 eV, D0(Ti+-S)=4.74±0.07 eV, D0(V+-S)=3.78±0.10 eV, D0(Y+-S)=5.49±0.18 eV, D0(Zr+-S)=5.69±0.10 eV, D0(Nb+-S)=5.20±0.21 eV. The theoretical data calculated in this article are 4.967 eV, 4.72 eV, 3.772 eV, 5.505 eV, 5.694 eV, 5.209 eV correspondingly which is in good agreement with the literature. Besides the recommended D0(M+-S) values, there are more data referring to D0(M+-S) in reactions of transition metal sulfides (M = Sc, Ti, V, Y, Zr, Nb) with oxygen-bearing substrates such as COS, CO, and CO2. It should be noted that different directions of the reaction corresponded to different observed values of bond dissociation energies (M+-S). The experimental D0 values for metal sulfide species from literature were calculated with high accuracy. In our calculations, we used the bond lengths from the literature calculated for various electronic configurations. Therefore, we assume that the previously obtained data allow us to define correlation between reagent electronic state and corresponding reaction direction

Sequential bond dissociation energies of (Th(CO)x)+,x = 1-6: Quantum computational studies alternative approach. The capabilities of mass-spectrometry in the determination of molecule geometry

The calculation problem of bond-dissociation energy BDE((CO)x-1Th+-CO), x = 1-6 was solved using the fundamental law of nature determining the dependence of chemical bond dissociation energy on its length. The recommended experimental values from literature are as follows bond dissociation energies BDE(Th+-CO)= 0.940.06 eV, BDE((CO)Th+-CO)=1.050.09 eV, BDE((CO)2Th+-CO)=1.090.05 eV, BDE((CO)3Th+-CO)=0.820.07 eV, BDE((CO)4Th+-CO)=0.630.05 eV, BDE((CO)5Th+-CO)=0.700.05 eV. The theoretical data calculated in this article are 0.934 eV, 1.056 eV, 1.082 eV, 0.82 eV, 0.634 eV, 0.708 eV correspondingly which is in good agreement with the literature. For the first time it was shown that experimental values of bond-dissociation energies, obtained with mass-spectrometry, can be successfully utilized in the calculations of the geometrical properties of molecules. The carried out calculations for thorium hexacarbonyl cation Th(CO)6+ determine its structure as tetragonal bipyramid. The found bond length values r((CO)x-1 Th+-CO) are 2.414 A and 2.444 A for equatorial and axial bonds correspondingly

CHEMICAL BONDS DISSOCIATION ENERGY

In previous publications dealing with experimental mass spectrometry of tungsten hexacarbonyl, hexafluoroacetylacetone and its bidentate metal complexes M(hfac)2; M = Cu, Pd the obtained data have been not adequately systematized. In this paper, we analyze the previously published experimental data of the various bond dissociation energy. A modified Yukawa potential, which is the exact solution of the problem dependence the chemical bond energy of its length, is used to analyze the experimental data. Experimental results of the formation of ions can be interpreted only in terms of the formation of fractionally charged quasi-particles. As an experimental technique, mass spectrometry of negative ions in electron resonance capture mode ranks next to the fractional quantum Hall effect in which fractional values of the charge quantization are observed. Also noted the possibility capture of electron with “negative” kinetic energy.</jats:p