title: Negative refraction via domain wall resonances in a homogeneous mixture of ferro- and nonmagnetic substances.
abstract: We deliver the general conditions on the synthetic proportions for a homogeneous mixture of ferro- and nonmagnetic substances to become left-handed. As an alternative for left-handed metamaterials, we consider mixing ferromagnetic materials with nonmagnetic microscopic particles. In the mixture, the ferromagnetic material provides the needed permeability via domain wall resonances at high frequencies, whereas the nonmagnetic material gives the required permittivity. Using the effective medium theory, we have found that when the concentration of the nonmagnetic particles falls into a certain range, the refractive index of the mixture is negative, n<0, which includes the double negative (ϵ<0  and μ<0) and other cases (e.g. ϵ<0  and μ>0). We finally give the requirements on the microscopic material properties for the ferromagnetic materials to reach the domain wall resonances at high frequencies.
authors.affiliation: Centro de Ciencias de la Materia Condensada, Universidad Nacional Autónoma de México, Apartado Postal 2681, CP 22800 Ensenada, Baja California, Mexico. weijingsong@siom.ac.cn
authors.forename: Jingsong
authors.initials: J
authors.lastname: Wei
authors.forename: Mufei
authors.initials: M
authors.lastname: Xiao