Phase-resolved x-ray ferromagnetic resonance measurements in fluorescence yield

Phase-resolved x-ray ferromagnetic resonance (XFMR) has been measured in fluorescence yield, extending the application of XFMR to opaque samples on opaque substrates. Magnetization dynamics were excited in a Co 50 Fe 50 (0.7)/Ni 90 Fe 10 (5) bilayer by means of a continuous wave microwave excitation, while x-ray magnetic circular dichroism (XMCD) spectra were measured stroboscopically at different points in the precession cycle. By tuning the x-ray energy to the L 3 edges of Ni and Fe, the dependence of the real and imaginary components of the element specific magnetic susceptibility on the strength of an externally applied static bias field was determined. First results from measurements on a Co 50 Fe 50 (0.7)/Ni 90 Fe 10 (5)/Dy(1) sample confirm that enhanced damping results from the addition of the Dy cap.