Left - handed materials in metallic magnetic granular composites

There is recently interests in the " left-handed " materials. In these materials the direction of the wave vector of electromagnetic radiation is opposite to the direction of the energy flow. We present simple arguments that suggests that magnetic composites can also be left-handed materials. However, the physics involved seems to be different from the original argument. In our argument, the imaginary part of the dielectric constant is much larger than the real part, opposite to the original argument. There has been interest recently in left-handed material [1, 2, 3], in which the direction of energy flow is opposite to the direction of the wave vector. The original material consists of arrays of rings and wires [2, 3]. We have recently proposed a different class of material consisting of metallic magnetic granular composites [4]. 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. In this paper, we present 1