Dynamic properties of soft magnetic materials in the shape of thin films and ribbons

Abstract

For the last two decades, the giant magneto impedance (GMI) effect has been studied mainly because of its potential use in high sensitivity magnetic field sensors. Nonetheless, magneto impedance response is not only important due to its applications but also its use in the investigation of magnetic properties of ferromagnetic materials. Especially at higher frequencies, order of GHz, GMI is closely related to the ferromagnetic resonance (FMR) effect. In this work, new experimental methods are introduced for the proper extraction of the FMR response from the GMI response which enables us to observe ferromagnetic resonance peaks, calculate the saturation magnetization, Gilbert damping parameter etc. For high frequency characterization, a state of art vector network analyzer is used. Moreover, sample’s response to external magnetic fields in different directions were analyzed by angle dependent magneto impedance measurements in which the angle between the external field and the sample axis varied. Magneto impedance of melt spun ribbons with various chemical compositions and different post manufacturing processes are measured and interpreted. Investigated samples include Standard FINEMET alloy ribbons which were annealed at various temperatures, New FINEMET alloy ribbons and other ribbons which were annealed with various magnitudes of current. By comparing the FMR response of ribbons annealed with various methods and conditions, we had a general idea about the effects of annealing on ferromagnetic materials’ magneto impedance response.