Seminars

# PIER Photon Science Colloquium: Femtosecond X-ray pulses to uncover ultrafast magnetization dynamics

## by Jan Lüning (Université Pierre et Marie Curie, Paris)

Friday, November 29, 2013 from to (Europe/Berlin)
at DESY Hamburg ( CFEL, Bldg. 99 )
 Description With the recent advent of XFELs and other femtosecond pulsed X-ray sources, it is now possible to apply advanced X-ray techniques to the investigation of ultrafast phenomena. The ability of these techniques to probe with high sensitivity individual components of complex materials has led in the field of femtomagnetism to novel insight into the underlying fundamental mechanisms. Exploiting the X-rays' short wavelength, we have combined femtosecond time resolution with nanometer spatial resolution and thus probed ultrafast magnetization dynamics on their relevant length scales. Our observations indicate that laser excitation of the valence electrons gives rise to a spin current affecting the sample's local magnetization. These results support the recently proposed model of superdiffusive spin transport.