2D surprises at the surface of 3D materials: confined electron systems in transition metal oxides

Abstract

The scope of this article is to review the state-of-the-art in the field of confined electron systems generated at the bare surfaces of transition metal oxides (TMOs). This scientific field is a prime example of a domain where two-dimensional physics and photoemission-based spectroscopic techniques have together set up the development of the story. The discovery of a high-mobility two-dimensional electron system (2DES) at interfaces of transition metal oxides has attracted an immense scientific interest due to new opportunities opened in the emerging field of oxide electronics. The subsequent paradigm shift from interfaces to the bare surfaces of TMOs made the confined electron system accessible to surface-sensitive spectroscopic techniques and this new era is the focus of the present article. We describe how results by means of Angle-Resolved Photoemission Spectroscopy (ARPES) establish the presence of confined electron carriers at the bare surface of SrTiO${}_3$(100), which exhibit complex physics phenomena such as orbital ordering, electron-phonon interactions and spin splitting. The key element behind the 2DES generation is oxygen vacancies. Moreover, we review the experimental evidence on the generation of 2DESs on surfaces with different orientation, as well as on different TMO substrates. The electronic structure of the confined electron system responds to such changes, thereby providing external means for engineering its properties. Finally, we identify new directions for future research by introducing a device-friendly fabrication protocol for the generation of 2DESs on TMO surfaces.

review on 2D electron gases on bare oxide surfaces: 15 pages, 11 figures

References in corpus (17)

• Magnetic effects at the interface between nonmagnetic oxides
• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Theory of spin-orbit coupling at LaAlO3/SrTiO3 interfaces and SrTiO3 surfaces
• A precise method for visualizing dispersive features in image plots
• Polar Discontinuity Doping of the LaVO_3/SrTiO_3 Interface
• Tailoring the nature and strength of electron-phonon interactions in the SrTiO${}_3$(001) two-dimensional electron liquid
• High mobility conduction at (110) and (111) LaAlO3/SrTiO3 interfaces
• Polaronic metal state at the LaAlO3/SrTiO3 interface
• Universal Fabrication of Two-Dimensional Electron Systems in Functional Oxides
• Control of a two-dimensional electron gas on SrTiO3(111) by atomic oxygen
• Structure and Correlation Effects in Semiconducting SrTiO${}_3$
• Orientational tuning of the Fermi sea of confined electrons at the SrTiO3 (110) and (111) surfaces
• A band structure scenario for the giant spin-orbit splitting observed at the Bi/Si(111) interface
• Engineering two-dimensional electron gases at the (001) and (101) surfaces of TiO2 anatase using light
• Ab initio study of the two-dimensional metallic state at the surface of SrTiO3: importance of oxygen vacancies
• Absence of Giant Spin Splitting in the Two-Dimensional Electron Liquid at the Surface of SrTiO${}_3$ (001)
• Chemical potential shift and gap-state formation in SrTiO${}_{3-\delta }$ revealed by photoemission spectroscopy

Cited by in corpus (5)

• Two-dimensional electron system at the magnetically tunable EuO/SrTiO${}_3$ interface
• High-density two-dimensional electron system induced by oxygen vacancies in ZnO
• Tunable two-dimensional electron system at the (110) surface of SnO${}_2$
• 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