The variation of the resonance field and the Gilbert damping parameter (G) with hcp Co film thickness was evaluated by measuring the X- and Qband ferromagnetic resonance (FMR) for buffer-layer/Co (2-16 nm)/Cu (1 nm)/Pt (15 nm) films. The two types of hcp Co films were deposited at a substrate temperature (Tsub) of either 400 °C or room temperature using a magnetron sputtering system. The G values for the Co films with Tsub = 400 °C exhibited a more rapid increase with decreasing thickness. In addition, the effective linewidth of FMR spectrum exhibited more rapid increase in the Q-band FMR for Tsub = 400 °C. The experimental results suggest that the spin-pumping is enhanced to a greater extent in the Co films fabricated at Tsub = 400 °C. Judging from the structural analysis of the Co films, it is possible that grain growth involving atomically flat surfaces of Co films might enhance the spin-pumping efficiency.
ASJC Scopus subject areas
- Physics and Astronomy(all)