  We report broadband ferromagnetic resonance (FMR) measurements based on a
coplanar waveguide (CPW) of ultrathin magnetic film structures that comprise
in-plane/out-of-plane decoupled layers deposited on nonmagnetic buffer layers
of various thickness or other buffer structures with a diverse sheet
resistance. We show that the excitation of the fundamental mode can be
substantially (up to 10 times) enhanced in the structures deposited on buffer
layers with a low sheet resistance in comparison to the structures deposited on
thin or weakly conducting buffer layers. The results are analyzed in terms of
shielding of the electromagnetic field of CPW by the conducting buffer layers.
The effect of enhancement of FMR absorption can be attractive for applications
in spintronic devices that utilize magnetization dynamics of ultrathin
ferromagnetic layers.
