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DS: Fachverband Dünne Schichten

DS 26: Oxides

DS 26.4: Vortrag

Donnerstag, 29. März 2007, 15:45–16:00, H34

Tunable Electron Gases in Oxide Hetrostructures — •Stefan Thiel¹, German Hammerl¹, Christoph Richter¹, Andreas Schmehl², Christof Schneider¹, and Jochen Mannhart¹ — ¹Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, Universitaetsstrasse 1, D-86159 Augsburg, Germany — ²Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802-5005, USA

Multilayers of complex oxides can show physical properties that are not found in either of their constituents. For example, a conducting, quasi-two dimensional electron gas is formed at the interface between the two insulating, dielectric perovskites LaAlO₃ and SrTiO₃ [1].

Here we report that the electron gas can be tuned to a very large extent by altering the thickness of the LaAlO₃ layers on the unit cell level. For LaAlO₃ layers that are up to 3 unit cells thick, highly insulating interfaces are obtained. In field effect transistor configurations using such interfaces as drain-source channels a quantum phase transition to the conducting state is readily achieved by gate fields. [2]. Upon change of their carrier densities with applied electric fields, the electron gas reacts with a pronounced memory effect.

[1] A. Ohtomo, H.Y. Hwang, A high-mobility electron gas at the LaAlO₃/SrTiO₃ heterointerface, Nature 427, 423-426 (2004)

[2] S. Thiel, G. Hammerl, A. Schmehl, C.W. Schneider, J. Mannhart, Tunable Quasi-Two-Dimensional Electron Gas in Oxide Heterostructures, Science 313, 1942-1945 (2006)