Consider that an incident plane wave is scattered by a homogeneous and isotropic magnetic sphere of finite radius. We determine, by means of the rigorous Mie theory, an exact expression for the time-averaged electromagnetic energy within this particle. For magnetic scatterers, we find that the value of the average internal energy in the resonance picks is much larger than the one associated with a scatterer with the same nonmagnetic medium properties. This result is valid even, and especially, for low size parameter values. Expressions for the contributions of the radial and angular field components to the internal energy are determined. For the analytical study of the weak absorption regime, we derive an exact expression for the absorption cross section in terms of the magnetic Mie internal coefficients. We stress that, although the electromagnetic scattering by particles is a well-documented topic, almost no attention has been devoted to magnetic scatterers. Our aim is to provide some new analytical results, which can be used for magnetic particles, and emphasize the unusual properties of the magnetic scatters, which could be important in some applications.
© 2010 Optical Society of America
Original Manuscript: October 19, 2009
Revised Manuscript: January 18, 2010
Manuscript Accepted: January 20, 2010
Published: April 7, 2010
Tiago José Arruda and Alexandre Souto Martinez, "Electromagnetic energy within magnetic spheres," J. Opt. Soc. Am. A 27, 992-1001 (2010)