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DF: Fachverband Dielektrische Festkörper

DF 20: Nonlinear dielectics, phase transitions, relaxors

DF 20.3: Vortrag

Donnerstag, 3. April 2014, 11:10–11:30, GER 37

Optically induced switching and bistability of the insulator-metal phase transition in vanadium dioxide nanoclusters — •Thorben Jostmeier¹, Johannes Zimmer², Achim Wixforth², Helmut Karl³, Hubert J. Krenner², and Markus Betz¹ — ¹Experimentelle Physik 2, TU Dortmund — ²Lehrstuhl für Experimentalphysik 1 and Augsburg Centre for Innovative Technologies, Universität Augsburg — ³Lehrstuhl für Experimentalphysik IV, Universität Augsburg

Bulk vanadium dioxide (VO₂) exhibits a insulator-metal phase transition (IMT) at a near ambient temperature of 68^∘C. Upon heating, VO₂ undergoes a structural and electronic change which is accompanied by a substantial change of the complex dielectric function. More specifically, the metallic phase features a strongly decreased transmission of near-infrared frequencies. A well known effect in nanoscopic VO₂ is a reversible thermal hysteresis of the IMT. Ion beam synthesised VO₂ : SiO₂ nanoclusters show a more pronounced thermal hysteresis with an supercooled state at room temperature. Additionally, diffraction gratings formed by site selective ion beam implantation show giant switching contrasts exceeding one order of magnitude.

The IMT can be also controlled using femtosecond near-infrared laser pulses. We for the first time show a broad fully reversible hysteresis/bistability in the optically induced phase transition of VO₂ : SiO₂ nanoclusters which allows for a permanent but still erasable switching of the IMT. These properties allow for the implementation of applications like ultrafast optical switches and optical storage devices.