title: Anisotropic two-dimensional electron gas at SrTiO3(110).
abstract: Two-dimensional electron gases (2DEGs) at oxide heterostructures are attracting considerable attention, as these might one day substitute conventional semiconductors at least for some functionalities. Here we present a minimal setup for such a 2DEG--the SrTiO3(110)-(4 × 1) surface, natively terminated with one monolayer of tetrahedrally coordinated 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 angle-resolved photoemission spectroscopy and theoretical results show that confinement along (110) is strikingly different from the (001) crystal orientation. In particular, the quantized subbands show a surprising "semiheavy" band, in contrast with the analog 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 the properties of this system.
authors.affiliation: Institute of Applied Physics, Vienna University of Technology, 1040 Vienna, Austria.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Wang
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Zhong
authors.forename: Xianfeng
authors.initials: X
authors.lastname: Hao
authors.forename: Stefan
authors.initials: S
authors.lastname: Gerhold
authors.forename: Bernhard
authors.initials: B
authors.lastname: Stöger
authors.forename: Michael
authors.initials: M
authors.lastname: Schmid
authors.forename: Jaime
authors.initials: J
authors.lastname: Sánchez-Barriga
authors.forename: Andrei
authors.initials: A
authors.lastname: Varykhalov
authors.forename: Cesare
authors.initials: C
authors.lastname: Franchini
authors.forename: Karsten
authors.initials: K
authors.lastname: Held
authors.forename: Ulrike
authors.initials: U
authors.lastname: Diebold
mesh_terms: D016880:Anisotropy; D002616:Chemical Engineering; D005740:Gases / Q000737:chemistry*; D008958:Models, Molecular; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D013324:Strontium / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D005740:Gases; D010087:Oxides; D014025:Titanium; C119252:strontium titanium oxide; D010100:Oxygen; D013324:Strontium
keywords: ARPES; electronic structure; oxide surface; perovskite; quantum confinement