Retarded modes in layered magnetic structures containing left-handed materials

We present a theoretical study of magnetic excitations in ferromagnetic film embedded in the left-handed materials (LHMs) and in superlattices composed of alternating layers of ferromagnetic materials and the LHMs. The dispersion relations of the surface polaritons in these systems are solved exactly. Some unusual retarded modes are found in these systems in comparison with the conventional ferromagnetic-dielectric multilayer structures. Magnetic excitations in the long-wavelength limit have also been discussed, and unusual magnetostatic modes have also been obtained.