Post-Deposition Annealing Effects on Ferromagnetic CoFeB Thin Films (Postprint)
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TOLEDO UNIV OH TOLEDO United States
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We investigate the role of annealing Co40Fe40B20 at different temperatures and how it affects the crystallinity and the ferromagnetic resonance FMR behavior. The onset of crystallization was shown to occur after annealing in nitrogen at 370 C for 1 h. The crystallization peak of the post-annealed Co40Fe40B20 was matched to the analysis of 110 Co7Fe3, due to secondary phase segregation. Magnetic force microscopy images show a pattern of magnetization ripples in the magnetic phase images for samples up to 250 C. The grain size of the Co7Fe3 110 was shown to increase from 20 to 56 nm when annealed above 370 C to 600 C. The segregated Co7Fe3 causes scattering of the FMR linewidth, which shifts the resonance peak location, broadens peak-to-peak linewidth, and causes an additional resonance peak to appear close to the uniform resonance of the amorphous phase. Annealing above 500 C leads to a complete phase change to Co7Fe3, which changes the FMR spectra back to a single resonance peak, shifted to lower elds with broader peak-to-peak linewidth of 71.2 kAm.
- Electricity and Magnetism