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MolES/Nano Seminar: David Cobden, University of Washington, Physics
WhenTuesday, Dec. 3, 2013, 2:30 – 3:30 p.m.

David Cobden, UW Physics
The phase diagram of vanadium dioxide

The metal-insulator transition (MIT) in vanadium dioxide is a candidate for numerous optical and electrical switching applications. However, it is a first-order solid-state phase transition, making it notoriously challenging to study reproducibly in any detail. The combination of the change in unit cell shape, the long range of elastic distortion, and latent heat, leads to domain structure, hysteresis, and cracking of even the highest quality samples. It is known that at the MIT two or more insulating phases (M1 and M2) occur in addition to the metallic phase (R), but the phase diagram relating these phases was not known. To determine it we studied single-crystal nanobeams of VO2 in a purpose-built nanomechanical strain apparatus. We were able to measure the transition temperature accurately for the first time to be 65.0 ± 0.1 °C, and found the surprising and suggestive result that the transition occurs precisely at the solid-state triple point of the metallic and two insulating phases.

Campus locationSavery Hall (SAV)
Campus room260
Event typesLectures/Seminars
Event sponsorsThe weekly seminar series organized by Molecular Engineering and Sciences Institute provides a forum for bringing national and international leaders in nanoscale science and technology to campus, and for graduate students enrolled in our Dual Ph.D. program in Nanotechnology to present their research. The campus and public are welcome to attend.…
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