Barium Ferrite Thin Films with Negative Nucleation Field for Self-biased Circulator Applications.

This paper presents a new method for BaM thin films having a negative nucleation field, consequently high squareness of film. Bi-layered BaM thin films were deposited by rf sputtering with high purity Ar and O
₂
gases on single crystal sapphire (000l) substrates. The bi-layer is composed of amorphous as a top layer and crystalline BaM films. A three-step rapid temperature annealing (RTA) was performed on bi-layered BaM film. All heat-treated BaM thin films were characterized by XRD, AFM, FE-SEM, VSM and surface profiler. The magnetic properties such as hysteresis loop, saturation magnetization and coercivity were investigated. Magnetic properties of this film could be applied to a self-biased circulator applications.