2016 CAP Congress / Congrès de l'ACP 2016

Photoinduced phase transition in vanadium dioxide: visualizing the time-dependent crystal potential using ultrafast electron diffraction data

14 Jun 2016, 19:02

2m

SITE Atrium (University of Ottawa)

Poster (Student, Not in Competition) / Affiche (Étudiant(e), pas dans la compétition) Condensed Matter and Materials Physics / Physique de la matière condensée et matériaux (DCMMP-DPMCM) DCMMP Poster Session with beer / Session d'affiches, avec bière DPMCM

Speaker

Laurent René de Cotret (McGill University)

Description

Vanadium dioxide is notable for exhibiting several low-temperature insulating phases and having a very well studied insulator-metal transition at ~68$^{\circ}C$ that is associated with a crystallographic change from monoclinic semiconductor to rutile metal. Using a combination of ultrafast electron diffraction (UED) and broadband spectroscopy, we have recently demonstrated that photoexcitation of monoclinic vanadium dioxide crystals below a threshold fluence induces a transition to a metastable state with monoclinic crystallography, but metal-like optical/electronic properties. This long-lived metallic phase appears to have no equilibrium analog. A detailed structural characterization of this phase, using a 3D visualization of electron scattering potential, is the subject of this poster. This visualization techniques confirms previous suspicions and offers more dynamical information than radial pair-correlation functions.