Capturing ultrafast magnetic dynamics by time-resolved soft x-ray magnetic circular dichroism

摘要

Experiments of time-resolved x-ray magnetic circular dichroism (Tr-XMCD) andresonant x-ray scattering at a beamline BL07LSU in SPring-8 with atime-resolution of under 50 ps are presented. A micro-channel plate is utilizedfor the Tr-XMCD measurements at nearly normal incidence both in the partialelectron and total fluorescence yield (PEY and TFY) modes at the L2,3absorption edges of the 3d transition-metals in the soft x-ray region. Theultrafast photo-induced demagnetization within 50 ps is observed on thedynamics of a magnetic material of FePt thin film, having a distinct thresholdof the photon density. The spectrum in the PEY mode is less-distorted both atthe L2,3 edges compared with that in the TFY mode and has the potential toapply the sum rule analysis for XMCD spectra in pump-probed experiments.