Yu. N. Kotyukov

Ferromagnetic resonance in polycrystalline ferrites with high magnetic anisotropy

The ferromagnetic resonance absorption line is computed in polycrystalline ferrites in the “independent grain” approximation taking account of the magnetic crystallographic and magnetostriction anisotropies. The results obtained show that the influence of elastic stresses on the shape of the absorption line is analogous to the effect of the magnetic crystallographic anisotropy.

Equation of the ferromagnetic resonance line in polycrystalline ferrites

Ferromagnetic resonance in polycrystalline ferrites is considered in the framework of the independent-grain model. It is shown that the ferromagnetic resonance absorption line can be obtained analytically from its moments. When a limited number of moments of the line are known explicitly, the method of Pearson curves is used to obtain the equation of the line. The obtained expression is analyzed and the resonance field and absorption line width deduced from the equation are compared with results obtained earlier.

Ferromagnetic resonance in media with an inhomogeneous saturation magnetization

The method of transition probabilities is used to calculate the line width of ferromagnetic resonance in a medium with an inhomogeneous saturation magnetization. It is shown that in addition to linear (with respect to the Fourier components of the function describing inhomogeneities) terms, the perturbation Hamiltonian must include also quadratic terms. The frequency dependence of the contribution of the porosity to ΔH is fundamentally different from the frequency dependence of the magnetic anisotropy contribution. This anisotropy contribution ΔHa(ω) decreases on increase in the frequency and has a maximum at ω = (2/3)ωM, whereas the porosity contribution ΔHpω increases on increase in the frequency and vanishes at ω = (2/3)ωM.

Influence of inhomogeneous exchange interaction on the moments of the ferromagnetic resonance lines in polycrystalline ferrites

From the viewpoint of the spin-wave approach to the theory of ferromagnetic resonance, the first four moments of the absorption line are calculated in this paper. It is shown that in addition to the magnetic dipole-dipole interaction, the inhomogeneous exchange interaction which has been neglected in previous papers exerts substantial influence on the asymmetry and peakedness of the ferromagnetic resonance line.

Approach to saturation of porous lithium ferrites

A study was made of how porosity affects the law of approach to saturation with respect to magnetization of porous lithium ferrites. The experimental results obtained are discussed within the framework of the theories of Néel and Schlömann.

Law describing the approach to saturation of porous anisotropic materials

A law is obtained for the approach to saturation with respect to magnetization for anisotropic magnetic materials with inhomogeneous saturation magnetization. In the calculation, the spin-wave formalism is used. The effect of an inhomogeneous exchange interaction on the approach to saturation is taken into account. The relations obtained are generalizations of the already known Neel and Holstein-Primakov formulas.

Dynamic magnetic susceptibility of polycrystalline ferrites

AbstractThe magnetic susceptibility of magnetized ferrites is described by the tensor of second rank

Sensitivity of ferromagnetic-resonance parameters to uniaxial compression in polycrystalline ferrites

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Dependence of the ferromagnetic-resonance parameters of polycrystalline ferrites on uniaxial elastic stress

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