Impact of Argon working pressure on the magnetic properties of sputtered Co60Fe20B20 thin films

Abstract

We present thorough investigation of the influence of Argon gas working pressure (PAr) on Co60Fe20B20 (CFB) thin films deposited on Si. The longitudinal magneto-optic Kerr effect measurements indicate that all films exhibit uniaxial anisotropy caused by the self-steering effect arising due to the oblique angle deposition. The coercive field is found to be sensitive to PAr during growth and reached to a minimal value of 0.766 kA/m at 0.147 Pa. The ferromagnetic resonance measurements revealed that PAr has a direct impact on the inhomogeneous linewidth, anisotropy, and the effective Gilbert damping constant (αeff). The low value of αeff ∼(4.16±0.10)×10−3is achieved in film grown at PAr∼0.147 Pa with negligible inhomogeneity and low anisotropy. At this optimum value of PAr, the surface roughness of the films is found to be lowest (∼ 4 Å). The observed changes in the static and dynamic magnetization properties in these CFB films on varying the PAr are correlated to the growth-rate-dependent changes in internal stress in the film. The choice of the value of PAr employed during sputtering of CFB films at room temperature is thus demonstrated as the simple control parameter for tuning its structural and magnetic properties for the development of spintronic memory applications.