title: Ultrafast structural dynamics of the orthorhombic distortion in the Fe-pnictide parent compound BaFe2As2.
abstract: Using femtosecond time-resolved hard x-ray diffraction, we investigate the structural dynamics of the orthorhombic distortion in the Fe-pnictide parent compound BaFe2As2. The orthorhombic distortion analyzed by the transient splitting of the (1 0 3) Bragg reflection is suppressed on an initial timescale of 35 ps, which is much slower than the suppression of magnetic and nematic order. This observation demonstrates a transient state with persistent structural distortion and suppressed magnetic/nematic order which are strongly linked in thermal equilibrium. We suggest a way of quantifying the coupling between structural and nematic degrees of freedom based on the dynamics of the respective order parameters.
authors.affiliation: Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Rettig
authors.affiliation: Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland.
authors.forename: S O
authors.initials: SO
authors.lastname: Mariager
authors.forename: A
authors.initials: A
authors.lastname: Ferrer
authors.affiliation: Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Grübel
authors.affiliation: Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland.
authors.forename: J A
authors.initials: JA
authors.lastname: Johnson
authors.forename: J
authors.initials: J
authors.lastname: Rittmann
authors.affiliation: Karlsruhe Institute of Technology , Institut für Festkörperphysik, D-76021 Karlsruhe, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Wolf
authors.affiliation: Institute for Quantum Electronics, ETH Zürich , CH-8093 Zürich, Switzerland.
authors.forename: S L
authors.initials: SL
authors.lastname: Johnson
authors.forename: G
authors.initials: G
authors.lastname: Ingold
authors.forename: P
authors.initials: P
authors.lastname: Beaud
authors.affiliation: Swiss Light Source, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland.
authors.forename: U
authors.initials: U
authors.lastname: Staub