Mixed Dimensionality of Confined Conducting Electrons in the Surface Region of SrTiO${}_3$

Abstract

Using angle-resolved photoemission spectroscopy, we show that the recently-discovered surface state on SrTiO${}_3$ consists of non-degenerate $t_{2g}$ states with different dimensional characters. While the $d_{xy}$ bands have quasi-2D dispersions with weak $k_z$ dependence, the lifted $d_{xz}$/$d_{yz}$ bands show 3D dispersions that differ significantly from bulk expectations and signal that electrons associated with those orbitals permeate the near-surface region. Like their more 2D counterparts, the size and character of the $d_{xz}$/$d_{yz}$ Fermi surface components are essentially the same for different sample preparations. Irradiating SrTiO${}_3$ in ultrahigh vacuum is one method observed so far to induce the "universal" surface metallic state. We reveal that during this process, changes in the oxygen valence band spectral weight that coincide with the emergence of surface conductivity are disproportionate to any change in the total intensity of the O $1s$ core level spectrum. This signifies that the formation of the metallic surface goes beyond a straightforward chemical doping scenario and occurs in conjunction with profound changes in the initial states and/or spatial distribution of near-$E_F$ electrons in the surface region.

Main text plus supplemental material. Total of 12 pages, 9 figures, 2 tables

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Cited by in corpus (46)

• Electronic structure of quantum materials studied by angle-resolved photoemission spectroscopy
• Tailoring the nature and strength of electron-phonon interactions in the SrTiO${}_3$(001) two-dimensional electron liquid
• Universal Fabrication of Two-Dimensional Electron Systems in Functional Oxides
• Control of a two-dimensional electron gas on SrTiO3(111) by atomic oxygen
• Creation of high mobility two-dimensional electron gases via strain induced polarization at an otherwise nonpolar complex oxide interface
• Giant negative magnetoresistance driven by spin-orbit coupling at the LAO/STO interface
• Surface magnetism of strontium titanate
• Hubbard band or oxygen vacancy states in the correlated electron metal SrVO${}_3$?
• Engineering two-dimensional electron gases at the (001) and (101) surfaces of TiO2 anatase using light
• Anomalous orbital structure in a spinel-perovskite interface $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$
• Topological states at the (001) surface of SrTiO3
• Origin of the anomalous mass renormalization in metallic quantum well states of correlated oxide SrVO${}_3$
• Absence of Giant Spin Splitting in the Two-Dimensional Electron Liquid at the Surface of SrTiO${}_3$ (001)
• Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO2 thin films
• Selective control of localised vs. delocalised carriers in anatase TiO2 through reaction with O2
• Mechanical dissipation from charge and spin transitions in oxygen deficient SrTiO_3
• Observation of a two-dimensional electron gas at CaTiO${}_3$ film surfaces
• Band-Order Anomaly at the γ-Al2O3/SrTiO3 Interface Drives the Electron-Mobility Boost
• Universal Structural Influence on the 2D Electron Gas at SrTiO${}_3$ Surfaces
• Spin galvanic effect at the conducting SrTiO3 surfaces
• Spin-texture induced by oxygen vacancies in Strontium perovskites (001) surfaces: A theoretical comparison between SrTiO3 and SrHfO3
• Controlling the magnetism of oxygen surface vacancies in strontium titanate $(\mathrm{SrTi}{\mathrm{O}}_3)$ through charging
• Evolution of the SrTiO${}_3$ surface electronic state as a function of LaAlO${}_3$ overlayer thickness
• Band Gap Modulation of SrTiO3 upon CO2 Adsorption
• 2D surprises at the surface of 3D materials: confined electron systems in transition metal oxides
• Two-dimensional electron systems in ATiO3 perovskites (A = Ca, Ba, Sr): control of orbital hybridization and order
• From low-field Sondheimer oscillations to high-field very large and linear magnetoresistance in a SrTiO${}_3$-based two-dimensional electron gas
• Semiclassical theory of anisotropic transport at LaAlO3/SrTiO3 interfaces under in-plane magnetic field
• Anisotropic Electronic Structure of the Two-Dimensional Electron Gas at the AlOx/KTaO3(110) interface
• Suppression of Surfaces States at Cubic Perovskite (001) Surfaces by CO${}_2$ Adsorption
• Theoretical models of Rashba spin splitting in asymmetric SrTiO3-based heterostructures
• Observation of Wannier-Stark localization at the surface of BaTiO${}_3$ films by photoemission
• Polar compensation at the surface of SrTiO3 (111)
• Quantum interference effects of out-of-plane confinement on two-dimensional electron systems in oxides
• Single spin-polarised Fermi surface in SrTiO${}_3$ thin films
• $d_{xz/yz}$ Orbital Subband Structures and Chiral Orbital Angular Momentum in the (001) Surface States of SrTiO${}_3$
• On the Origin of the Two-Dimensional Electron Gas at the CdO (100) Surface
• Soft x-ray irradiation induced metallization of layered TiNCl
• Ultrafast Modification of the Polarity at LaAlO${}_3$/SrTiO${}_3$ Interfaces
• Structure and ferromagnetic instability of the oxygen-deficient SrTiO${}_3$ surface
• Hard x-ray angle-resolved photoemission from a buried high-mobility electron system
• Anomalous Quasiparticle Reflection from the Surface of a ${}^3$He-${}^4$He Dilute Solution
• Duality and degeneracy lifting in two-dimensional electron liquids on SrTiO${}_3$(001)
• Three-dimensionality of mobile electrons at X-ray-irradiated LaAlO${}_3$/SrTiO${}_3$ interfaces
• A two-dimensional electron gas at the (001) surface of ferromagnetic EuTiO${}_3$(001)
• Surface state at $BaSn{O}_3$ evidenced by angle-resolved photoemission spectroscopy and ab initio calculations