title: Nanoscale interface confinement of ultrafast spin transfer torque driving non-uniform spin dynamics.
abstract: Spintronics had a widespread impact over the past decades due to transferring information by spin rather than electric currents. Its further development requires miniaturization and reduction of characteristic timescales of spin dynamics combining the sub-nanometre spatial and femtosecond temporal ranges. These demands shift the focus of interest towards the fundamental open question of the interaction of femtosecond spin current (SC) pulses with a ferromagnet (FM). The spatio-temporal properties of the impulsive spin transfer torque exerted by ultrashort SC pulses on the FM open the time domain for probing non-uniform magnetization dynamics. Here we employ laser-generated ultrashort SC pulses for driving ultrafast spin dynamics in FM and analysing its transient local source. Transverse spins injected into FM excite inhomogeneous high-frequency spin dynamics up to 0.6 THz, indicating that the perturbation of the FM magnetization is confined to 2 nm.
authors.affiliation: Physical Chemistry Department, Fritz Haber Institute of Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Ilya
authors.initials: I
authors.lastname: Razdolski
authors.affiliation: Physical Chemistry Department, Fritz Haber Institute of Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Alexandr
authors.initials: A
authors.lastname: Alekhin
authors.affiliation: Physical Chemistry Department, Fritz Haber Institute of Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.|Moscow Technological University MIREA, Vernadsky Ave. 78, 119454 Moscow, Russia.
authors.forename: Nikita
authors.initials: N
authors.lastname: Ilin
authors.affiliation: Faculty of Chemistry, University of Duisburg-Essen, Universitätsstr. 5, 45141 Essen, Germany.
authors.forename: Jan P
authors.initials: JP
authors.lastname: Meyburg
authors.affiliation: Universität Göttingen, Institut für Materialphysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Roddatis
authors.affiliation: Faculty of Chemistry, University of Duisburg-Essen, Universitätsstr. 5, 45141 Essen, Germany.
authors.forename: Detlef
authors.initials: D
authors.lastname: Diesing
authors.affiliation: Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany.
authors.forename: Uwe
authors.identifier: 0000-0002-1506-4491
authors.initials: U
authors.lastname: Bovensiepen
authors.affiliation: Physical Chemistry Department, Fritz Haber Institute of Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.|Institute of Physics, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 3, 06120 Halle, Germany.
authors.forename: Alexey
authors.initials: A
authors.lastname: Melnikov