Nonreciprocal electromagnetic properties of nanocomposites at microwave frequencies

This is the authors' abstract. We don't add key points for this paper.

We report on the effects of composition and external magnetic field on the microwave permeability tensor of Ni∕γ-Fe₂O₃ nanocomposites. When compared to the zero-field case, the field measurements of the permeability tensor μ exhibit nonzero off-diagonal components giving evidence of the nonreciprocity of wave propagation in these nanostructures. We observe that the diagonal and off-diagonal elements of ⃡μ of these nanocomposites depend sensitively on their Ni content and of the applied static magnetic field. These experimental results are analyzed within a recently developed multiscale modeling [S. Mallegol et al., Phys. Rev. B 68, 174422 (2003)] and can be understood as arising from magnetostatic intergranular interactions via a mean-field approximation. The application of these heterogeneous nanomaterials open possibilities for the design of field-controlled nonreciprocal components used in microwave integrated circuit technology.