Tuning the spin pumping characteristics in Ni81Fe19/CuNx bilayer films

Abstract

We demonstrate that the spin pumping effect can be effectively tuned with nitriding the nonmagnetic layer in ferromagnetic/nonmagnetic (FM/NM) bilayer system. Series of Ni81Fe19/CuNx bilayer films were prepared by magnetron sputtering with different nitrogen partial pressures from 0% to 20%. The static magnetic properties of the Ni81Fe19/CuNx bilayer films were studied by vibrating sample magnetometer and dynamic magnetic properties was studied using a coplanar waveguide vector-network-analyzer ferromagnetic resonance spectrometer with an in-plane configuration. The results reveal that the static magnetic properties are not noticeably changed with capping a nitrified copper layer. Both the linewidth and the Gilbert damping parameter are strongly influenced by the nitrogen partial pressure during the copper layer nitride process. The spin-mixing conductance of the NiFe/CuNx bilayer films was quantified from the peak-to-peak linewidth of ferromagnetic resonance spectra based on the model of the spin pumping.