Regensburg 2016 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 73: Heterostructures and Interfaces (Joint session of HL and O, organized by HL)
HL 73.6: Talk
Thursday, March 10, 2016, 11:15–11:30, H17
Ultrafast multi-terahertz nanoscopy of strained vanadium dioxide nanobeams — •Markus A. Huber1, Markus Plankl1, Max Eisele1, Robert E. Marvel2, Fabian Sandner1, Tobias Korn1, Christian Schüller1, Richard F. Haglund2, Rupert Huber1, and Tyler L. Cocker1 — 1Department of Physics, University of Regensburg, 93040 Regensburg, Germany — 2Department of Physics and Astronomy and Interdisciplinary Materials Science Program, Vanderbilt University, Nashville, Tennessee 37235-1807, USA
Long regarded as a model system for studying insulator-to-metal transitions, vanadium dioxide features a rich phase diagram including at least three insulating states and one metallic state. Recently, the effects of strain on the transition temperature and nanoscale domain structure have been brought into focus. In this regard scattering-type near-field microscopy in the multi-terahertz regime [10-100 THz] has been proven to be a valuable tool for imaging the spatial heterogeneity of the transition. However, so far no time-resolved near-field studies have been undertaken. Here, we show the local pump-probe behavior of a single-crystalline vanadium dioxide nanobeam upon near-infrared photoexcitation. We probe with an ultrafast multi-terahertz pulse and see a modulation of the photoconductivity along the cR-axis of the wire. This modulation qualitatively matches the different switching susceptibilities inside the wire upon thermal heating. We therefore propose that the switching susceptiblity is built into the wire already at room-temperature, most likely by strain.