Ferromagnetic Relaxation and Magnetic Properties of Co40Fe40B20 Thin Films

Abstract

The Co40Fe40B20 thin films with varying thickness using silicon dioxide (SiO2) as substrate were fabricated by magnetron sputtering system (ULVAC, Japan) with a base pressure P = 10−8 Torr to understand magnetodynamic interactions and structural properties. The samples were characterized using X-band ferromagnetic resonance experiments at room temperature. The XRD pattern shows that the thin film is amorphous and we got a strong peak (400) of substrate silicon dioxide (SiO2). The SEM result of Co40Fe40B20 thin film demonstrates that it has uniform and homogeneous morphology. It has been observed from ferromagnetic resonance (FMR) results that the thin film depicts anisotropic behavior and easy axis lies out of the plane. The dependence of the resonance fields on the angle between the normal of the film and out of plane dc magnetic field indicates the presence of uniaxial magnetic anisotropy associated with thickness of Co40Fe40B20 thin films. The inplane and out-of-plane angular dependences of the resonance field (HR) and line width (ΔHpp) of FMR spectra were measured and explained using the Landau–Lifshitz–Gilbert equation. The origin of magnetic damping has been discussed by considering spin–orbit, s–d interactions, and two magnonscattering mechanism. Some background molecular vibrations at wave number 2000 and 3800 cm−1 in three samples are also identified from FTIR, which further show that background molecular vibrations can be reduced by decreasing the size. This study will be helpful to understand spin transfer torque (STT) and the timescale for magnetization reversal in the spintronic devices