Oxide interface electron gases

LaAlO₃ grown on (001) SrTiO₃

Also called LAO/STO, oxide 2DEG

an interface, not a sheet depends on form

A boundary case that sharpens what ‘two-dimensional material’ means. Put two insulating oxides together and a sheet of mobile electrons appears where they meet – two-dimensional in its behaviour, but locked inside a three-dimensional crystal rather than something you could peel off. It shows that 2D electron physics does not require a layered material, and it hosts superconductivity and magnetism that can be switched with a voltage.

Data sheet

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Kind of sheet: an interface, not a sheet
A conducting layer where two crystals meet
Behaves as: depends on form
Band gap: Both parent oxides are wide-gap insulators (LaAlO₃ ~5.6 eV, SrTiO₃ ~3.2 eV); the interface is metallic, superconducting below ~0.2 K, and shows signatures of magnetism
Thickness: Electron gas confined within roughly 1–10 nm of the interface
Structure: Not a free-standing sheet: a conducting layer a few nanometres thick forms on the SrTiO₃ side of the interface once the polar LaAlO₃ film is at least four unit cells thick
Space group: LaAlO₃: bulk R3c
SrTiO₃: bulk Pm3m
Bulk: the Materials Project crystal linked below
Stability: Chemically robust, but oxygen vacancies created during growth can add parasitic bulk conduction; oxygen annealing is needed to isolate genuine interface conductivity.
First made: 2004 – high-mobility electron gas at the LaAlO₃/SrTiO₃ interface, Ohtomo and Hwang
Materials Project: LaAlO₃
SrTiO₃
Computed crystal structure and properties

Compare with other materials

Key properties

Conductivity switches on abruptly when LaAlO₃ reaches four unit cells (~1.5 nm) on TiO₂-terminated SrTiO₃
Two-dimensional superconductivity below ~0.2 K, tunable with a back-gate voltage
Strong, gate-tunable Rashba spin–orbit coupling
Carrier densities around 10¹³ cm⁻²
Conducting nanostructures can be written and erased with a conductive AFM tip

How it is made

Pulsed laser deposition or MBE of LaAlO₃ on TiO₂-terminated SrTiO₃(001), counting unit cells by in-situ RHEED
Related interfaces on KTaO₃, where superconductivity appears at higher temperatures on some crystal orientations
Free-standing oxide membranes released from sacrificial layers, which make oxide heterostructures transferable

Uses, and how close they are

Oxide electronics, spin–charge conversion and gate-tunable superconducting deviceslab
Reconfigurable nanoelectronics written with an AFM tiplab

Readiness runs lab → prototype → pilot → deployed.

Open problems

What mix of electronic reconstruction at the polar interface, oxygen vacancies and cation intermixing creates the electron gas?
How are superconductivity and magnetism, normally incompatible, arranged at the same interface?
Can freestanding oxide membranes combine oxide interface physics with van der Waals stacking?

Going deeper

Short notes for specialists. Choose a lens in the header and yours comes first.

For theoreticians · your lens

The polar-discontinuity model explains the critical thickness qualitatively; quantitative work needs slab DFT with sufficiently thick layers, realistic defects (oxygen vacancies, La/Sr intermixing), and spin–orbit coupling for the Ti t₂g subband ordering. Superconductivity in SrTiO₃ at very low carrier densities remains a theoretical puzzle.

For experimentalists · your lens

Control SrTiO₃ termination by etching and annealing, and count LaAlO₃ unit cells from RHEED oscillations. Distinguish interface conduction from oxygen-vacancy bulk conduction by comparing films grown at different oxygen pressures and by post-annealing in oxygen.

For engineers · your lens

No manufacturable device yet: single-crystal SrTiO₃ substrates are small and expensive, and superconductivity needs millikelvin temperatures. Freestanding oxide membranes may eventually make these functions integrable on silicon.

Recent news

The newest items tagged LaAlO₃/SrTiO₃, from the news feed updated 5 Oct 2026.

Preprintnot yet peer reviewed 15 Sep 2026 arXiv

Layer- and Orbital-Selective Mott Physics Driving Dimensional Crossover in Nickelate Superlattices

The design of quantum materials to manipulate dimensionality and electronic correlations is a central focus in the exploration of emergent phenomena. We propose a new correlated quantum material platform for realizing a layer- and orbital-selective Mott transition (LOSMT) in a nickelate heterostructure by combining…

TheoryLaAlO₃/SrTiO₃

Preprintnot yet peer reviewed 30 Nov 2025 arXiv

Universal Fabrication of Graphene/Perovskite Oxide Hybrid Heterostructures

Hybrid heterostructures composed of graphene and perovskite oxides provide a promising platform for exploiting synergetic interfacial functionalities. Conventional fabrication methods of the hybrid heterostructures rely on transferring graphene grown on metallic substrates-- a process that is time-consuming…

ExperimentGraphene LaAlO₃/SrTiO₃

All 2 items tagged LaAlO₃/SrTiO₃ in the news feed · RSS feed for LaAlO₃/SrTiO₃

Key references

A high-mobility electron gas at the LaAlO₃/SrTiO₃ heterointerfaceOhtomo & Hwang · Nature 427, 423 (2004)cited by 4,717doi:10.1038/nature02308
Tunable quasi-two-dimensional electron gases in oxide heterostructuresThiel et al. · Science 313, 1942 (2006)cited by 1,555doi:10.1126/science.1131091
Superconducting interfaces between insulating oxidesReyren et al. · Science 317, 1196 (2007)cited by 2,739doi:10.1126/science.1146006