High frequency complex permeability of iron particles in a nonmagnetic matrix

Abstract

The effective permeability (μeff) was measured and calculated for composites consisting of micron- or submicron-sized nanocrystalline iron particles embedded in a nonmagnetic matrix. The intrinsic permeability of iron particles was obtained from the calculation for a random spatial distribution of magnetic domains and its analytical model is derived from the Landau-Lifshitz-Gilbert equation. In the calculation, each grain is assumed to be a single magnetic domain because of its nano size. The effective permeability was calculated using three methods—Bruggeman’s effective medium theory, extended Bruggeman’s effective medium theory with the consideration of the skin effect, and a simulation method which was developed in the present work. The skin effect was considered in our simulation work. Our simulation agrees well with the experimental data. Our work has shown clearly that the magnetic domain structure with a random spatial distribution of magnetic easy axes and the skin effect need to be considered to calculate the complex permeability of polycrystalline magnetic materials.

High-frequency magnetic properties of FeNi3–SiO2 nanocomposite synthesized by a facile chemical method

“…In the past decades, nanostructured magnetic materials have attracted intensive interest because of their excellent physical, catalytic, magnetic properties and their crucial applications in diverse fields, including catalysts [1], biomedical treatments and analysis [2], magnetic fluids [3], magnetic photonic crystals [4,5], high-density magnetic storage media [6,7], microwave absorbing materials [8][9][10][11], high-frequency soft magnetic materials [12][13][14][15][16]. In particular, the rapid developments of wireless communication devices have required miniature magnetic components, such as inductor and transformer, to be operated at high frequency.…”

Microwave complex permeability of planar anisotropy carbonyl-iron particles

“…The resonance frequency (f r ) is defined as the corresponding frequency for the maximum imaginary permeability. According to the Bruggeman's effective medium theory [26], the static permeability of PACI composite (500 rpm) is approximate 27.5, and the resonance frequency is 4.3 GHz. The product of the static permeability and the resonance frequency for PACI particles is 114.0 GHz, which is much higher than the Snoek's constant 40 GHz for isotropy carbonyl-iron particles.…”

High frequency complex permeability of flake-shaped Fe74Cr2Mo2Sn2P10Si4B4C2 particle composite material

“…(1)) or the extended Bruggeman effective medium theory [4,9], we can not calculate the effective permeability of particle oriented-distributed composites. …”

“…The theory was developed for calculating the frequency dependence of permeability, considering the grain structure, domain structure, effect of the distribution of magnetic easy axes [3,4]. However, the effect of the orientation ratio of flake-shaped particles on the complex permeability was not considered yet.…”