Growth of Co(2)FeAl Heusler alloy thin films on Si(100) having very small Gilbert damping by Ion beam sputtering

The influence of growth temperature T(s) (300–773 K) on the structural phase ordering, static and dynamic magnetization behaviour has been investigated in ion beam sputtered full Heusler alloy Co(2)FeAl (CFA) thin films on industrially important Si(100) substrate. The B2 type magnetic ordering is established in these films based on the clear observation of the (200) diffraction peak. These ion beam sputtered CFA films possess very small surface roughness of the order of subatomic dimensions (<3 Å) as determined from the fitting of XRR spectra and also by AFM imaging. This is supported by the occurrence of distinct Kiessig fringes spanning over the whole scanning range (~4°) in the x-ray reflectivity (XRR) spectra. The Gilbert damping constant α and effective magnetization 4πM(eff) are found to vary from 0.0053 ± 0.0002 to 0.0015 ± 0.0001 and 13.45 ± 00.03 kG to 14.03 ± 0.04 kG, respectively. These Co(2)FeAl films possess saturation magnetization ranging from 4.82 ± 0.09 to 5.22 ± 0.10 μ(B)/f.u. consistent with the bulk L2(1)-type ordering. A record low α-value of 0.0015 is obtained for Co(2)FeAl films deposited on Si substrate at T(s) ~ 573 K.