title: A photoinduced metal-like phase of monoclinic VO₂ revealed by ultrafast electron diffraction.
abstract: The complex interplay among several active degrees of freedom (charge, lattice, orbital, and spin) is thought to determine the electronic properties of many oxides. We report on combined ultrafast electron diffraction and infrared transmissivity experiments in which we directly monitored and separated the lattice and charge density reorganizations that are associated with the optically induced semiconductor-metal transition in vanadium dioxide (VO2). By photoexciting the monoclinic semiconducting phase, we were able to induce a transition to a metastable state that retained the periodic lattice distortion characteristic of the semiconductor but also acquired metal-like mid-infrared optical properties. Our results demonstrate that ultrafast electron diffraction is capable of following details of both lattice and electronic structural dynamics on the ultrafast time scale.
authors.affiliation: Department of Physics, Center for the Physics of Materials, McGill University, Montreal, Quebec H3A 2T8, Canada.
authors.forename: Vance R
authors.initials: VR
authors.lastname: Morrison
authors.affiliation: Department of Physics, Center for the Physics of Materials, McGill University, Montreal, Quebec H3A 2T8, Canada.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Chatelain
authors.affiliation: Department of Physics, Center for the Physics of Materials, McGill University, Montreal, Quebec H3A 2T8, Canada.
authors.forename: Kunal L
authors.initials: KL
authors.lastname: Tiwari
authors.affiliation: Institut National de la Recherche Scientifique, Centre Énergie Matériaux et Télécommunications, Université du Québec, Varennes, Quebec J3X 1S2, Canada.
authors.forename: Ali
authors.initials: A
authors.lastname: Hendaoui
authors.affiliation: Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Bruhács
authors.affiliation: Institut National de la Recherche Scientifique, Centre Énergie Matériaux et Télécommunications, Université du Québec, Varennes, Quebec J3X 1S2, Canada.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Chaker
authors.affiliation: Department of Physics, Center for the Physics of Materials, McGill University, Montreal, Quebec H3A 2T8, Canada. Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada. bradley.siwick@mcgill.ca.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Siwick