An In Situ Anneal Study of Graded Anisotropy FePtCu Films

作者：Fang Yeyu^*; Dumas R K; Zha C L; Akerman Johan

来源：IEEE Magnetics Letters, 2011, 2: 5500104.

DOI：10.1109/LMAG.2011.2114332

• Hard magnetic materials
• FePtCu films
• graded anisotropy
• in situ magnetic characterization
• magnetic recording media

We provide a detailed study of how the anisotropy (K-u) gradient in a compositionally graded FePtCu film gradually develops as a function of the postannealing temperature (T-A). By utilizing the in situ annealing and magnetic characterization capabilities of a physical property measurement system, the evolution of the induced K-u gradient is elucidated. For low T-A, the sample primarily remains in the low-K-u A1 phase. At intermediate T-A, the gradual development of an A1 to L1(0) anisotropy gradient occurs. As T-A is further increased, a well-developed L1(0) gradient is realized. Finally, annealing temperatures greater than 475 degrees C reduce the gradient until the film is effectively uniform for T-A >= 525 degrees C and higher, presumably due to interdiffusion of the Cu through the film thickness. The resulting coercivity shows a nonmonotonic dependence on T-A with an initial steep increase as the L1(0) fraction of the sample increases, a local minimum at T-A = 525 degrees C where the gradient vanishes, and a final increase as the uniform L1(0) film orders completely.

• 出版日期2011