Negative index metamaterials in magnetic composites

In this paper, we will review some works on negative index metamaterials in magnetic composites, basically based on our recent works. First, we explore the condition of the existence of negative index meta-materials made of magnetic materials. We will point out that the left-handed materials in the magnetic materials are closely related to the wave polarization and magnetic damping. Then, the layer magnetic structure with negative index of refraction is proposed. We will discuss some factors that affect the negative index of the structure, and give an expression of index of refraction at long wave limitation. Some simulation and experimental results are given. After that, considering the magnetic and electric loss of the materials we propose a new phase diagram for the lossy metamaterials. We will point out that the existence of let-handed material accompany with the single-negative negative index materials, and the loss of let-handed material is always smaller than that of ingle-negative negative index materials. Finally, we will talk about the special characters of magnetic metamateials and their possible applications.