Air-CPW test structure for broadband permeability spectra measurements of thin ferromagnetic films

This paper demonstrates a novel technique based on a coplanar waveguide (CPW) test structure for broadband characterization of the intrinsic permeability spectra of thin ferromagnetic films. This measurement is based on the analysis of S-parameters obtained using a CPW test structure connected to Vector Network Analyzer (VNA) in transmission. The specific feature of the test structure is a small 50Ω `air-CPW' section loaded with a thin layer of the material under test (MUT). This feature allows independent measurements and component separation of complex permeability and permittivity spectra of thin conductive ferromagnetic films. The technique can be conveniently applied to the characterization of both continuous and patterned magnetic films.