Magnetic damping constant of Co2FeSi Heusler alloy thin film

Co2FeSi films were prepared using magnetron sputtering technique on Cr buffer layers and MgO(001) substrates at various annealing temperatures. We investigated the crystal structures, magnetic properties (M-s and H-c), surface roughness, and magnetic damping constants (alpha) of the prepared Co2FeSi films. Out-of-plane angular dependences of the resonance field and the linewidth of the ferromagnetic resonance spectra were measured and fitted using the Landau-Lifshitz-Gilbert equation to determine the damping constant. The as-deposited Co2FeSi film exhibited an amorphous and disordered structure; the alpha value was 0.008. In contrast, the Co2FeSi films annealed over 300 degrees C showed epitaxial growth and had a (001)-oriented and L2(1) ordered structure. Both disordered and L2(1) ordered Co2FeSi films showed similar alpha values. (C) 2007 American Institute of Physics.