title: Tunable one-dimensional electron gas carrier densities at nanostructured oxide interfaces.
abstract: The emergence of two-dimensional metallic states at the LaAlO3/SrTiO3 (LAO/STO) heterostructure interface is known to occur at a critical thickness of four LAO layers. This insulator to-metal transition can be explained through the "polar catastrophe" mechanism arising from the divergence of the electrostatic potential at the LAO surface. Here, we demonstrate that nanostructuring can be effective in reducing or eliminating this critical thickness. Employing a modified "polar catastrophe" model, we demonstrate that the nanowire heterostructure electrostatic potential diverges more rapidly as a function of layer thickness than in a regular heterostructure. Our first-principles calculations indicate that for nanowire heterostructures a robust one-dimensional electron gas (1DEG) can be induced, consistent with recent experimental observations of 1D conductivity at LAO/STO steps. Similar to LAO/STO 2DEGs, we predict that the 1D charge density decays laterally within a few unit cells away from the nanowire; thus providing a mechanism for tuning the carrier dimensionality between 1D and 2D conductivity. Our work provides insight into the creation and manipulation of charge density at an oxide heterostructure interface and therefore may be beneficial for future nanoelectronic devices and for the engineering of novel quantum phases.
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States.
authors.forename: Houlong L
authors.initials: HL
authors.lastname: Zhuang
authors.affiliation: Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States.
authors.forename: Lipeng
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States.
authors.forename: Haixuan
authors.initials: H
authors.lastname: Xu
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States.|Computer Science and Mathematics Division, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States.
authors.forename: P R C
authors.initials: PR
authors.lastname: Kent
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States.
authors.forename: P
authors.initials: P
authors.lastname: Ganesh
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Bethel Valley Road, Oak Ridge, Tennessee 37831, United States.
authors.forename: Valentino R
authors.initials: VR
authors.lastname: Cooper