Effects of nominal intermediate layer on microstructure and magnetic property in CoCrPtTa/CrTi thin films

Two kinds of nominal intermediate layers were introduced in CoCrPtTa/CrTi bilayer magnetic thin films. The materials used for the intermediate layer were identical to the magnetic layer (CoCrPtTa) and the underlayer (CrTi) materials, which simulated two extreme interfacial conditions in terms of the crystal lattice mismatch. The in-plane coercivity varied in a broad range when the sputtering pressure for the intermediate layer increased. The degradation of coercivity by lattice mismatch was analyzed. Reference bilayer X/CrTi (X=CoCrPtTa/CrTi) films were prepared and studied by X-ray diffraction (XRD), transmission electron microscopy (TEM)-select area diffraction (SAD), atomic force microscopy (AFM) and X-ray reflectivity (XRR). Morphology, interfacial roughness and interdiffusion were discussed to explain the coercivity behavior, which suggested that both the interfacial factors and epitaxial growth should be included as two compete mechanisms to explain the magnetic properties of the recording films.