Magnetic characterization of on-chip integrated layer of substituted Sr-M hexaferrite beyond 10 GHz

The recent advent of telecommunication usage demands the frequency of operation to be in X-band (8-10 GHz) in near future. Finding a suitable magnetic material that exhibits sufficiently high permeability with ferromagnetic resonance (FMR) frequency at that band is a huge challenge and, therefore, hindering the progress of devices like inductors and noise suppressors.[1] The family of Hexaferrites is one of the most promising choices due to their reasonably high permeability and inherently large magnetocrystalline anisotropy that results in a very high FMR frequency.[2] However, measurement of FMR frequency among other high frequency magnetic characteristics beyond 10 GHz is extremely tricky and error-prone. The problem escalates during the measurement of thin film. Among the various techniques, coplanar waveguide (CPW) based measurements are very simple but extremely sensitive to noise.[3] One of the ways to improve signal to noise ratio is to reduce the CPW line-width so as to deliver more power along with the integration of magnetic layer directly on to it.