Magnetic losses in composite materials

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Magnetic losses in composite materials. / Ramprecht, Jörgen; Sjöberg, Daniel.

In: Journal of Physics D: Applied Physics, Vol. 41, No. 13, 135005, 2008.

Research output: Contribution to journalArticle

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TY - JOUR

T1 - Magnetic losses in composite materials

AU - Ramprecht, Jörgen

AU - Sjöberg, Daniel

PY - 2008

Y1 - 2008

N2 - We discuss some of the problems involved in homogenization of a composite material built from ferromagnetic inclusions in a nonmagnetic background material. The small signal permeability for a ferromagnetic spherical particle is combined with a homogenization formula to give an effective permeability for the composite material. The composite material inherits the gyrotropic structure and resonant behaviour of the single particle. The resonance frequency of the composite material is found to be independent of the volume fraction, unlike dielectric composite materials. The magnetic losses are described by a magnetic conductivity which can be made independent of frequency and proportional to the volume fraction by choosing a certain bias. Finally, some concerns regarding particles of small size, i.e. nanoparticles, are treated and the possibility of exciting exchange modes are discussed. These exchange modes may be an interesting way to increase losses in composite materials.

AB - We discuss some of the problems involved in homogenization of a composite material built from ferromagnetic inclusions in a nonmagnetic background material. The small signal permeability for a ferromagnetic spherical particle is combined with a homogenization formula to give an effective permeability for the composite material. The composite material inherits the gyrotropic structure and resonant behaviour of the single particle. The resonance frequency of the composite material is found to be independent of the volume fraction, unlike dielectric composite materials. The magnetic losses are described by a magnetic conductivity which can be made independent of frequency and proportional to the volume fraction by choosing a certain bias. Finally, some concerns regarding particles of small size, i.e. nanoparticles, are treated and the possibility of exciting exchange modes are discussed. These exchange modes may be an interesting way to increase losses in composite materials.

U2 - 10.1088/0022-3727/41/13/135005

DO - 10.1088/0022-3727/41/13/135005

M3 - Article

VL - 41

JO - Journal Physics D: Applied Physics

JF - Journal Physics D: Applied Physics

SN - 1361-6463

IS - 13

M1 - 135005

ER -