title: Ultrafast Spin Density Wave Transition in Chromium Governed by Thermalized Electron Gas.
abstract: The energy and momentum selectivity of time- and angle-resolved photoemission spectroscopy is exploited to address the ultrafast dynamics of the antiferromagnetic spin density wave (SDW) transition photoexcited in epitaxial thin films of chromium. We are able to quantitatively extract the evolution of the SDW order parameter Δ through the ultrafast phase transition and show that Δ is governed by the transient temperature of the thermalized electron gas, in a mean field description. The complete destruction of SDW order on a sub-100 fs time scale is observed, much faster than for conventional charge density wave materials. Our results reveal that equilibrium concepts for phase transitions such as the order parameter may be utilized even in the strongly nonadiabatic regime of ultrafast photoexcitation.
authors.affiliation: Department of Physical Chemistry, Fritz-Haber-Institut of the Max Planck Society, Faradayweg 4-6, Berlin 14915, Germany.
authors.forename: C W
authors.initials: CW
authors.lastname: Nicholson
authors.affiliation: Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Monney
authors.affiliation: Max-Born-Institut, Max-Born-Strasse 2A, 12489 Berlin, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Carley
authors.affiliation: Max-Born-Institut, Max-Born-Strasse 2A, 12489 Berlin, Germany.|Fachbereich Physik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Frietsch
authors.affiliation: Max-Born-Institut, Max-Born-Strasse 2A, 12489 Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Bowlan
authors.affiliation: Fachbereich Physik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Weinelt
authors.affiliation: Department of Physical Chemistry, Fritz-Haber-Institut of the Max Planck Society, Faradayweg 4-6, Berlin 14915, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Wolf