Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Impedance of nanometer thickness ferromagnetic Co40Fe40B20 films | Jen et al. Nanoscale Research Letters 2011 6 468 http content 6 1 468 o Nanoscale Research Letters a SpringerOpen Journal NANO REVIEW Open Access Impedance of nanometer thickness ferromagnetic Co40Fe40B20 films Shien Uang Jen1 Tzu Yang Chou1 and Chi Kuen Lo2 Abstract Nanocrystalline Co40Fe40B20 films with film thickness if 100 nm were deposited on glass substrates by the magnetron sputtering method at room temperature. During the film deposition period a dc magnetic field h 40 Oe was applied to introduce an easy axis for each film sample one with h L and the other with h w where L and w are the length and width of the film. Ferromagnetic resonance FMR ultrahigh frequency impedance IM dc electrical resistivity p and magnetic hysteresis loops MHL of these films were studied. From the MHL and r measurements we obtain saturation magnetization 4nMs kG anisotropy field Hk kG and r 168 . From FMR we can determine the Kittel mode ferromagnetic resonance FMR-K frequency fFMRK 1 963 MHz. In the h L case IM spectra show the quasi-Kittel-mode ferromagnetic resonance QFMR-K at f0 and the Walker-mode ferromagnetic resonance FMR-W at fn where n 1 2 3 and 4. In the h w case IM spectra show QFMR-K at F0 and FMR-W at Fn. We find that f0 and F0 are shifted from fFMRK respectively and fn Fn. The in-plane spin-wave resonances are responsible for those relative shifts. PACS No. . q . q Keywords spin-wave resonance impedance magnetic films Introduction It is known that impedance IM of an ferromagnetic FM material is closely related to its complex permeability p pR i pI where pR and px are the real and imaginary parts in the high-frequency f range 1 2 . Past experience has also shown that there should exist a cutoff frequency fc where pR crosses zero and pI reaches maximum 3 for each FM material. According to Ref. 3 fc increases as the thickness of the FM sample decreases and finally reaches an upper limit. The thickness .
