Influences of sputtering gas pressure and gas flow rate on microwave characteristics of FeCoAlO thin films

In this work, the influences of sputtering gas pressure and gas flow rate on the microwave characteristics of FeCoAlO thin films are investigated. All the high-frequency permeability spectra are discussed based on the Landau-Lifshitz-Gilbert equation. Although no obvious dependences on the pressure can be identified from the static magnetic hysteresis loops, the parameters obtained from the permeability spectra show strong dependences on the sputtering gas pressure. At 2 mTorr, the lowest damping factor and the highest anisotropy field are located. With the increase of gas flow rate, the resonance frequency decreases and frequency linewidth increases. Discussions infer that these dependences should be ascribed to the inner stress of the sputtered film which is influenced by the sputtering gas conditions.