title: Enhanced photosusceptibility near Tc for the light-induced insulator-to-metal phase transition in vanadium dioxide.
abstract: We use optical-pump terahertz-probe spectroscopy to investigate the near-threshold behavior of the photoinduced insulator-to-metal (IM) transition in vanadium dioxide thin films. Upon approaching Tc a reduction in the fluence required to drive the IM transition is observed, consistent with a softening of the insulating state due to an increasing metallic volume fraction (below the percolation limit). This phase coexistence facilitates the growth of a homogeneous metallic conducting phase following superheating via photoexcitation. A simple dynamic model using Bruggeman effective medium theory describes the observed initial condition sensitivity.
authors.affiliation: Center for Integrated Nanotechnologies, MS K771, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hilton
authors.forename: R P
authors.initials: RP
authors.lastname: Prasankumar
authors.forename: S
authors.initials: S
authors.lastname: Fourmaux
authors.forename: A
authors.initials: A
authors.lastname: Cavalleri
authors.forename: D
authors.initials: D
authors.lastname: Brassard
authors.forename: M A
authors.initials: MA
authors.lastname: El Khakani
authors.forename: J C
authors.initials: JC
authors.lastname: Kieffer
authors.forename: A J
authors.initials: AJ
authors.lastname: Taylor
authors.forename: R D
authors.initials: RD
authors.lastname: Averitt