title: Influence of the pump pulse wavelength on the ultrafast demagnetization of Gd(0 0 0 1) thin films.
abstract: We studied the magnetization dynamics of gadolinium metal after femtosecond laser excitation recording the x-ray magnetic circular dichroism in reflection (XMCD-R) at the Gd M5absorption edge. Varying the photon energy of the pump pulse allows us to change the initial energy distribution of photoexcited carriers. The overall similar response for excitation with 0.95, 1.55 and 3.10 eV photons at comparable pump fluences indicates that ultrafast ballistic carrier transport leads to a homogeneous energy distribution on the femtosecond timescale in the probed sample volume. Differences are observed in the initial ultrafast demagnetization magnitude. They are attributed to an enhanced spin-flip probability at higher electron energies characterizing the non-thermal electron distribution.
authors.affiliation: Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany.
authors.forename: Kamil
authors.initials: K
authors.lastname: Bobowski
authors.forename: Markus
authors.initials: M
authors.lastname: Gleich
authors.forename: Niko
authors.initials: N
authors.lastname: Pontius
authors.forename: Christian
authors.initials: C
authors.lastname: Schüßler-Langeheine
authors.forename: Christoph
authors.initials: C
authors.lastname: Trabant
authors.forename: Marko
authors.initials: M
authors.lastname: Wietstruk
authors.forename: Björn
authors.initials: B
authors.lastname: Frietsch
authors.forename: Martin
authors.initials: M
authors.lastname: Weinelt