Hard x-ray reflectivities (Mo radiation with ) of the three samples studied. From top to bottom: multilayer, Py film, Py/Cu multilayer. The reflectivity scans are shifted against each other in thevertical direction for clarity. The solid lines represent fits to the data points.
Schematics of the experimental setup. A single bunch x-ray pulse is reflected from the stripline into the detector. The circularly polarized incident x-ray beam is tuned to the resonance edge of the respective element. The magnetization precession is excited by a pulsed Oersted field generated prior to the probe x-ray pulse. The delay time between exciting field pulse and the probing x-ray pulse is scanned.
Magnetic hysteresis determined from the asymmetry as measured at the first Bragg peak of the multilayers and the corresponding scattering angle for the Py layer. The multilayer Bragg peaks enhance considerably the magnetic contrast.
Delay scan for the Py(25 nm) sample at incident angles of and . Several delay scans are shown for different bias fields applied from 3.75 Oe to 30 Oe. Pairs of scans for one field value but different incident angles are shifted by a factor of 0.3; scans for different field values are shifted by a factor of 1. The solid lines show fits to the data points.
Comparison of delay scans with fit results (solid lines) for the two multilayers (top panel) and Py/Cu (bottom panel) taken at the 1st (full symbols) and the 2nd (open symbols) Bragg peak. All scans are shifted against each other in the vertical direction by constant factors for clarity. Pairs of scans for one field value but different Bragg peaks are shifted by a factor of 0.3; scans for different field values are shifted by a factor of 1.
Comparison of the magnetization precession in Py/Cu and multilayers. The frequencies are nearly the same at a given bias field, but the amplitudes are smaller for Cu than for interlayers. The scans for different bias fields are vertically shift for clarity.
Experimental results for decay times and precessional frequencies in Py, , and Py/Cu samples. The top panels show the dependence of the precessional frequency of the respective system as a function of bias field. The bottom panels show the decay times as a function of bias field for all three samples as recorded at the first and second Bragg peak or corresponding angles of the single Py layer.
Layer thicknesses (d) and interface mean square roughness () for the samples used in this study. All values in nm.
Summary of the fit results for the decay time and the Landéfactor g. For the g-factor, the saturation magnetization value was used. The numbers in brackets indicate the error bars, BP is the Bragg peak.
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