Adjustable Microwave Magnetic Spectra of Metamaterials Based on Ferromagnetic Film Laminates

A resonant RLC circuit with a magnetic core has been investigated experimentally and theoretically as a promising metamaterial cell design. Laminates of multilayer ferromagnetic films serve as a magnetic core. The ferromagnetic resonance frequency of the bare laminate core is above 1 GHz. An intensive magnetic absorption peak is obtainable at lower frequencies due to a resonant wire coiled around the core. Such magnetic metamaterials seem promising for applications that require high magnetic loss at frequencies of hundreds of megahertz. This paper focuses on efficient approaches to adjusting the location of magnetic loss peak in magnetic metamaterials. High-frequency permeability of the metamaterial samples has been measured in a rectangular waveguide. It is shown that by varying the geometry, structure, and composition of the measured metamaterial samples, the magnetic spectra can be radically changed. Excitation of electromagnetic resonance in the ferromagnetic core with the resonant wire is discussed within the frame of the quasi-static approximation.