Gilbert damping of CoFe-alloys

Abstract

We report structural, magnetic and dynamic properties of polycrystalline coxfe1-x-alloy films on sapphire, silicon, and mgo substrates across the full composition range, by using a vector network analyser ferromagnetic resonance measurement technique (vna-fmr), superconducting quantum interference device magnetometry (squid) and x-ray diffraction (xrd). in the approximate vicinity of 28% co, we observe a minimum of the damping parameter, associated with a reduction in the density of states to a minimum value at the fermi energy level. for films on all substrates, we find magnetic damping of the order of 4-5 . 10(-3), showing that the substrate does not play a major role. using a post-annealing process, we report a decrease of the magnetic damping down to 3-4 . 10(-3). we find that the saturation magnetization depends approximately reciprocally on the damping parameter with varying alloy composition.