In most magnetic devices with thin films, the magnetic properties are governed by not only the intrinsic properties but also the microstructure. To realize high performance in magnetic devices, understanding the correlation between magnetic properties and microstructure is important. In this study, the development of ferromagnetic thin films for high-density recording media and large output current perpendicular to plane giant magnetoresistance devices are reviewed. Based on the experimental data, the research direction for next-generation high-areal-density magnetic recording is discussed.
Review Article by awardee of MSJ Achievement Award 2021
A method for obtaining magnetic permeability of thin film by the direct contact probe was developed and the measurement error of permeability was reduced. We analyzed the frequency dependence of a current path inside the magnetic thin film using by finite element method. The magnetic permeability was corrected in consideration of the frequency dependence of the high-frequency current inside the magnetic thin film. The permeability of CoNbZr film (5 mm x 5 mm, 2 μm in thickness) was optimized by the method, and measured permeability was roughly agreed with the theoretical value up to 4 GHz.