26 research outputs found
Theoretical investigation on the possibility of preparing left-handed materials in metallic magnetic granular composites
We investigate the possibility of preparing left-handed materials in metallic
magnetic granular composites. Based on the effective medium approximation, we
show that by incorporating metallic magnetic nanoparticles into an appropriate
insulating matrix and controlling the directions of magnetization of metallic
magnetic components and their volume fraction, it may be possible to prepare a
composite medium of low eddy current loss which is left-handed for
electromagnetic waves propagating in some special direction and polarization in
a frequency region near the ferromagnetic resonance frequency. This composite
may be easier to make on an industrial scale. In addition, its physical
properties may be easily tuned by rotating the magnetization locally.Comment: 5 figure
Electron energy loss and induced photon emission in photonic crystals
The interaction of a fast electron with a photonic crystal is investigated by
solving the Maxwell equations exactly for the external field provided by the
electron in the presence of the crystal. The energy loss is obtained from the
retarding force exerted on the electron by the induced electric field. The
features of the energy loss spectra are shown to be related to the photonic
band structure of the crystal. Two different regimes are discussed: for small
lattice constants relative to the wavelength of the associated electron
excitations , an effective medium theory can be used to describe the
material; however, for the photonic band structure plays an
important role. Special attention is paid to the frequency gap regions in the
latter case.Comment: 12 pages, 7 figure
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