Comparison of time-resolved x-ray magnetic circular dichroism measurements in reflection and transmission for layer-specific precessional dynamics measurements

We present experimental techniques to measure magnetization precession of individual layers in a “spin-valve” trilayer. Precessional motions of individual Ni81Fe19 and Co93Zr7 layers have been separated in Ni81Fe19∕Cu∕Co93Zr7 using ±45ps time-resolved x-ray magnetic circular dichroism (tr-XMCD) at Fe and Co edges. We compare the efficacy of two experimental configurations in this paper. Pulsed-field tr-XMCD measurements in reflectivity are compared with resonant-field tr-XMCD measurements in transmission. Despite the order of magnitude larger angles of precession excited in pulsed-field reflectivity measurements, data quality is found to be superior in resonant-field transmission measurements. Relative roles of sample preparation and timing jitter in the different techniques are discussed.