European XFEL Science Seminar

Ultrafast spin and magnetization dynamics in rare earth metals

by Martin Weinelt (Physics Department, Freie Universität Berlin)

E1.173 (Campus Schenefeld XHQ)


Campus Schenefeld XHQ

On which timescale do the band structure and spin polarization of a ferromagnet change after femtosecond laser excitation and how do they affect the magnetization dynamics? To answer these questions we perform time-, spin-, and angle-resolved photoemission experiments with optical laser pulses and higher-order harmonic radiation and investigate the transient magnetization by time-resolved X-ray magnetic circular dichroism in reflection. For the local ferromagnets gadolinium and terbium, we show that exchange splitting, spin polarization, and transient magnetic moment can respond on significantly different timescales. This allows us to distinguish between contributions of spin-flip scattering, spin-lattice coupling, and spin transport to the ultrafast magnetization dynamics.