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TT: Fachverband Tiefe Temperaturen

TT 8: Low-Dimensional Systems: Oxide Hetero-Interfaces

TT 8.1: Vortrag

Montag, 16. März 2015, 09:30–09:45, H 3010

Transport properties of LaAlO₃/SrTiO₃ nanostructures — •Alexander Müller¹, Mohsin Minhas¹, Hans-Helmuth Blaschek¹, and Georg Schmidt^1,2 — ¹Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle (Saale), Germany — ²Interdisziplinäres Zentrum für Materialwissenschaften, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle (Saale) , Germany

Deposition of thin layers of LaAlO₃ (LAO) on top of a TiO₂ terminated SrTiO₃ (STO) substrate with Pulsed Laser Deposition results in a two dimensional electron gas at the interface [1]. Using PMMA as resist and etch mask this electron gas can be patterned by a standard electron-beam lithography step and subsequent Reactive Ion Etching to remove the LAO.

With this process transport structures with minimum dimensions in the sub-micron regime have been fabricated. The structures include gaps of approx. 100 nm width. Transport through the gap is characterized by taking I/V characteristics in a standard four point geometry from room temperature down to 1.5 K.

Between 1.5 and 30 K up to a threshold voltage of tens of mV no current is observed. Beyond that threshold voltage the current increases dramatically. Within a few tens of mV the current can increase by up to eight orders of magnitude. The threshold voltage is temperature dependent in a non-monotonic fashion and all I/V curves are free of any hysteresis.

[1] A. Ohtomo, H.Y. Hwang, Nature 427, 6973 (2004)