Fa. Pinheiro et al., Multiple scattering of electromagnetic waves in disordered magnetic media:Localization parameter, energy transport velocity and diffusion constant, BRAZ J PHYS, 31(1), 2001, pp. 65-70
We review some of our recent results concerning the single and multiple ele
tromagnetic scattering by magnetic spherical particles. For a single electr
omagnetic scattering we show that the magnetic contribution alters, when co
mpared to nonmagnetic scattering, the behavior of the cross sections and me
an cosine of the scattering angle ([cos theta]). For ferromagnetic particle
s, resonances may occur even in the small-particle limit when the particle
radius is much smaller than the wavelength. The resonances increase the cro
ss-sections while [cos theta] is diminished, and even may become negative.
Several quantities such the Ioffe-Regel parameter for localization are calc
ulated for the multiple scattering regime. We show that magnetic scattering
favors the observation of localization of electromagnetic waves in three d
imensions. Further, this is also verified for dynamical experiments, where
we show that the diffusion constant can be very small. Since the magnetic p
ermeability of the scatterers can vary significatively around the Curie-Wei
ss critical temperature, experiments should be done on the microwave region
and the scatterers should be soft ferrites. Some aspects of such experimen
t are presented.