title: Ultrafast dynamics of charge density waves in 4H(b)-TaSe2 probed by femtosecond electron diffraction.
abstract: The dynamics of the photoinduced commensurate-to-incommensurate charge density wave (CDW) phase transition in 4H(b)-TaSe(2) are investigated by femtosecond electron diffraction. In the perturbative regime, the CDW re-forms on a 150-ps time scale, which is two orders of magnitude slower than in other transition-metal dichalcogenides. We attribute this to a weak coupling between the CDW carrying T layers and thus demonstrate the importance of three-dimensionality for the existence of CDWs. With increasing optical excitation, the phase transition is achieved, showing a second-order character, in contrast to the first-order behavior in thermal equilibrium.
authors.affiliation: Laser Research Institute, Stellenbosch University, Stellenbosch 7600, South Africa.
authors.forename: N
authors.initials: N
authors.lastname: Erasmus
authors.forename: M
authors.initials: M
authors.lastname: Eichberger
authors.forename: K
authors.initials: K
authors.lastname: Haupt
authors.forename: I
authors.initials: I
authors.lastname: Boshoff
authors.forename: G
authors.initials: G
authors.lastname: Kassier
authors.forename: R
authors.initials: R
authors.lastname: Birmurske
authors.forename: H
authors.initials: H
authors.lastname: Berger
authors.forename: J
authors.initials: J
authors.lastname: Demsar
authors.forename: H
authors.initials: H
authors.lastname: Schwoerer