RT Journal Article
SR Electronic
T1 Band structure evolution during the ultrafast ferromagnetic-paramagnetic phase transition in cobalt
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP e1602094
DO 10.1126/sciadv.1602094
VO 3
IS 3
A1 Eich, Steffen
A1 Plötzing, Moritz
A1 Rollinger, Markus
A1 Emmerich, Sebastian
A1 Adam, Roman
A1 Chen, Cong
A1 Kapteyn, Henry Cornelius
A1 Murnane, Margaret M.
A1 Plucinski, Lukasz
A1 Steil, Daniel
A1 Stadtmüller, Benjamin
A1 Cinchetti, Mirko
A1 Aeschlimann, Martin
A1 Schneider, Claus M.
A1 Mathias, Stefan
YR 2017
UL http://advances.sciencemag.org/content/3/3/e1602094.abstract
AB The evolution of the electronic band structure of the simple ferromagnets Fe, Co, and Ni during their well-known ferromagnetic-paramagnetic phase transition has been under debate for decades, with no clear and even contradicting experimental observations so far. Using time- and spin-resolved photoelectron spectroscopy, we can make a movie on how the electronic properties change in real time after excitation with an ultrashort laser pulse. This allows us to monitor large transient changes in the spin-resolved electronic band structure of cobalt for the first time. We show that the loss of magnetization is not only found around the Fermi level, where the states are affected by the laser excitation, but also reaches much deeper into the electronic bands. We find that the ferromagnetic-paramagnetic phase transition cannot be explained by a loss of the exchange splitting of the spin-polarized bands but instead shows rapid band mirroring after the excitation, which is a clear signature of extremely efficient ultrafast magnon generation. Our result helps to understand band structure formation in these seemingly simple ferromagnetic systems and gives first clear evidence of the transient processes relevant to femtosecond demagnetization.