title: Hot-electron-driven enhancement of spin-lattice coupling in Gd and Tb 4f ferromagnets observed by femtosecond x-ray magnetic circular dichroism.
abstract: Femtosecond x-ray magnetic circular dichroism was used to study the time-dependent magnetic moment of 4f electrons in the ferromagnets Gd and Tb, which are known for their different spin-lattice coupling. We observe a two-step demagnetization with an ultrafast demagnetization time of 750 fs identical for both systems and slower times which differ sizeably with 40 ps for Gd and 8 ps for Tb. We conclude that spin-lattice coupling in the electronically excited state is enhanced up to 50 times compared to equilibrium.
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, BESSY II, Albert-Einstein-Strasse 15, 12489 Berlin, Germany.
authors.forename: Marko
authors.initials: M
authors.lastname: Wietstruk
authors.forename: Alexey
authors.initials: A
authors.lastname: Melnikov
authors.forename: Christian
authors.initials: C
authors.lastname: Stamm
authors.forename: Torsten
authors.initials: T
authors.lastname: Kachel
authors.forename: Niko
authors.initials: N
authors.lastname: Pontius
authors.forename: Muhammad
authors.initials: M
authors.lastname: Sultan
authors.forename: Cornelius
authors.initials: C
authors.lastname: Gahl
authors.forename: Martin
authors.initials: M
authors.lastname: Weinelt
authors.forename: Hermann A
authors.initials: HA
authors.lastname: Dürr
authors.forename: Uwe
authors.initials: U
authors.lastname: Bovensiepen