Penetration Depth of Transverse Spin Current in Ferromagnetic Metals
  The line width of the ferromagnetic resonance (FMR) spectrum of Cu/CoFeB/Cu/Co/Cu is studied. Analyzing the FMR spectrum by the theory of spin pumping, we determined the penetration depth of the transverse spin current in the Co layer. The obtained penetration depth of Co is 1.7 nm. 
Tomohiro Taniguchi, Satoshi Yakata, Hiroshi Imamura, Yasuo Ando