Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 16: Electronic Structure and Spin-Orbit Interaction II

O 16.1: Talk

Monday, March 31, 2014, 16:00–16:15, GER 38

Anisotropic two-dimensional electron gas at SrTiO₃(110) protected by its native overlayer — •Zhiming Wang¹, Zhicheng Zhong², Xianfeng Hao¹, Stefan Gerhold¹, Bernhard Stöger¹, Michael Schmid¹, Jaime Sánchez-Barriga³, Andrei Varykhalov³, Cesare Franchini⁴, Karsten Held², and Ulrike Diebold¹ — ¹Institute of Applied Physics, Vienna University of Technology, Vienna, Austria — ²Institute of Solid State Physics, Vienna University of Technology, Vienna, Austria — ³BESSY, Albert-Einstein-Str. 15, D-12489 Berlin, Germany — ⁴Faculty of Physics and Center for Computational Material Science, University of Vienna, Vienna, Austria

Two dimensional electron gases (2DEGs) at oxide heterostructures are attracting considerable attention, as these might substitute conventional semiconductors for novel electronic devices. Here we present a minimal set-up for such a 2DEG – the SrTiO₃(110)-(4×1) surface, natively terminated with one monolayer of chemically-inert titania. Oxygen vacancies induced by synchrotron radiation migrate underneath this overlayer; this leads to a confining potential and electron doping such that a 2DEG develops. Our angular resolved photoemission spectroscopy (ARPES) and theoretical results show that confinement along (110) is strikingly different from a (001) crystal orientation. In particular the quantized subbands show a surprising “semi-heavy” band, in contrast to the analogue in the bulk, and a high electronic anisotropy. This anisotropy and even the effective mass of the (110) 2DEG is tunable by doping, offering a high flexibility to engineer properties of this system. This work is supported by ERC Advanced Grant and FWF.