A detailed comparative Ferromagnetic resonance study of pulsed laser deposited Co40Fe40B20 thin films, before and after annealing, was under taken. The dependence of resonance field (Hres) and peak-to-peak linewidth (ΔHpp) on film thickness, annealing temperature, and magnetic field orientation is examined. ‘In-plane’ (IP) and ‘out-of-plane’ (OP) angular dependence of the resonance fields, (IP:Hres(ψ); OP:Hres(α)), were measured at T = 150 and 295 K for the as deposited (as-) to annealed (an-) thin film samples to determine IP (HK∥) and OP (HK⊥) uniaxial anisotropy fields. Variation of Hres(ψ) and Hres(α) on sample geometry demonstrate that the uniaxial magnetic anisotropy is present in as- and an-thin films of Co40Fe40B20. The effective magnetic anisotropy (Kueff) increases after nanocrystallization in CoFeB films indicates that the exchange interactions are unable to average out the local …