title: Ultrafast structural phase transition driven by photoinduced melting of charge and orbital order.
abstract: We use femtosecond x-ray diffraction to probe directly the structural dynamics of a charge ordered and orbitally ordered thin film of La0.42Ca0.58MnO3 initiated by an ultrafast optical pulse. At low excitation fluences we observe the displacive excitation of a coherent optical A(g) phonon. Under high excitation conditions we observe a complete phase transition within 1 ps via the disappearance of a superlattice reflection. The initial step of the phase transition occurs on a time scale significantly faster than the 200 fs time resolution of our experiment.
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland. paul.beaud@psi.ch
authors.forename: P
authors.initials: P
authors.lastname: Beaud
authors.forename: S L
authors.initials: SL
authors.lastname: Johnson
authors.forename: E
authors.initials: E
authors.lastname: Vorobeva
authors.forename: U
authors.initials: U
authors.lastname: Staub
authors.forename: R A
authors.initials: RA
authors.lastname: De Souza
authors.forename: C J
authors.initials: CJ
authors.lastname: Milne
authors.forename: Q X
authors.initials: QX
authors.lastname: Jia
authors.forename: G
authors.initials: G
authors.lastname: Ingold