Laser-induced ultrafast demagnetization in the presence of a nanoscale magnetic domain network.
Femtosecond magnetization phenomena have been challenging our understanding for over a decade. Most experiments have relied on infrared femtosecond lasers, limiting the spatial resolution to a few micrometres. With the advent of femtosecond X-ray sources, nanometric resolution can now be reached, which matches key length scales in femtomagnetism such as the travelling length of excited 'hot' electrons on a femtosecond timescale. Here we study laser-induced ultrafast demagnetization in [Co/Pd](30) multilayer films, which, for the first time, achieves a spatial resolution better than 100 nm by using femtosecond soft X-ray pulses. This allows us to follow the femtosecond demagnetization process in a magnetic system consisting of alternating nanometric domains of opposite magnetization. No modification of the magnetic structure is observed, but, in comparison with uniformly magnetized systems of similar composition, we find a significantly faster demagnetization time. We argue that this may be caused by direct transfer of spin angular momentum between neighbouring domains.
Laboratoire d'Optique Appliquée, ENSTA ParisTech-CNRS UMR 7639-École polytechnique, Chemin de la Hunière, Palaiseau, France. boris.vodungbo@ensta-paristech.fr
Boris
B
Vodungbo
Julien
J
Gautier
Guillaume
G
Lambert
Anna Barszczak
AB
Sardinha
Magali
M
Lozano
Stéphane
S
Sebban
Mathieu
M
Ducousso
Willem
W
Boutu
Kaigong
K
Li
Bharati
B
Tudu
Marina
M
Tortarolo
Ranjit
R
Hawaldar
Renaud
R
Delaunay
Victor
V
López-Flores
Jacek
J
Arabski
Christine
C
Boeglin
Hamed
H
Merdji
Philippe
P
Zeitoun
Jan
J
Lüning