13–20 Sept 2013
Magnus-Haus of the German Physical Society
Europe/Berlin timezone

Verwey Transition in Magnetite: How fast does an insulator become a metal?

Not scheduled
20m
Magnus-Haus of the German Physical Society

Magnus-Haus of the German Physical Society

Am Kupfergraben 7 10117 Berlin

Speaker

Ms Roopali Kukreja (Stanford University/ SLAC National Accelerator Laboratory)

Description

Magnetite (Fe3O4), is the first oxide where a relationship between electrical conductivity and fluctuating/localized charges was observed, with a drop in conductivity by two orders of magnitude at T=123K. The Verwey transition is accompanied by a structural change from monoclinic to cubic symmetry. Despite decades of research and indications that charge and orbital ordering play an important role, the mechanism behind the Verwey transition is yet unclear. Recently, three-Fe-site lattice distortions called trimerons have been identified as the true microscopic face of electronic order in low temperature insulating phase. We studied the real time response of insulating magnetite to optical excitation with ultrafast soft X-ray scattering. We discover this to be a two-step process. After an initial femtosecond destruction of individual trimerons in the corresponding lattice, we observe a phase separation into residual insulating trimeron and cubic metallic phases on a 1.5 ± 0.2 picosecond timescale.

Primary author

Ms Roopali Kukreja (Stanford University/ SLAC National Accelerator Laboratory)

Co-authors

Alexander Föhlisch (Helmholtz-Zentrum berlin für Materialien und Energie) Mr Bjorn Brauer (SLAC National Accelerator Laboratory) Mr Christian Back (Universität Regensburg, Physikalisches INstitut) Christoph Trabant (II. Physikalisches Institut Universität zu Köln / G-ISRR Helmholtz-Zentrum Berlin) Chun Fu Chang (Universität zu Köln, II. Physikalisches Institut) Daniele Fausti (Department of Physic, University of Trieste) Dilling Zhu (SLAC National LAccelerator Laboratory) Donghui Lu (SLAC National Accelerator Laboratory) Fabio Novelli (Department of Physic, University of Trieste) Fulvio Parmigiani (Department of Physics, Universty of trieste) Hermann Dürr (SLAC National Accelerator Laboratory) Joshua J Turner (SLAC National Accelerator Laboratory) Luc Pathey (SwissFEL, Paul Scherrer Institut) M. A. Hossain (SLAC National Accelerator Laboratory) MIng Yi (SLAC National Accelerator Laboratory) Mr Marcel Buchholz (Universität zu Köln, II. Physikalischen Institut) Mariano Trigo (SLAC National Accelerator Laboratory) Ms Marita Doehler (Universität zu KölnII. Physikalisches Institut) Mr Mark S. Golden (UNiversity Amsterdam, Va de Waals-Zeeman Institute) Martin Beye (Helmholtz Zentrum Berlin für Materialien und Energie) Ms Martina Esposito (Department of Physic, University of Trieste) Niko Pontius (Helmholtz-Zentrum Berlin für Materialien und Energie) Ms Nomi Sorgenfrei (Universität Hamburg, Department of Physics and Centerfor Free-Electron Laser Science) Mr Oleg Krupin (European XFEL GmbH) Ms Patricia Metcalf (Purdue University, School of Materials Engeneering) Dr Patrick Kirchmann (SLAC National Accelerator Laboratory) Rob Moore (SLAC National Accelerator Laboratory) Torsten Kachel (Helmholtz-Zentrum berlin für Materialien und Energie) Wei-Cheng Lee (SLAC National Accelrator Laboratory) Mr Wilfried Wurth (INiversität Hamburg, Department of Physics and center for Free electron Laser Science) Mr William F. Schlotter (SLAC National Accelerator Laboratory) Yi-De Chuang (Advanced Light Source)

Presentation materials