Electron Spin Flip Relaxation by One Magnon Processes: Application to   the Gadolinium surface band
  The "s-f model", also known as the ferromagnetic Kondo lattice, contains a description of band electrons coupled to localized spins which is an appropriate description of the magnetic part of the low-energy physics of Gd metal. Here the model is used to estimate the lifetime broadening of the minority spin component of the surface electron band in ferromagnetic gadolinium metal at temperatures below the Curie temperature. The low temperature result 0.10 eV agrees nicely with a measurement by Fedorov et al. 
Philip B. Allen