Atomic-Level Precision and Strong Oxidation Unite in GOALL-Epitaxy for Advanced Material Growth

Sydney, Australia (SPX) May 15, 2025
Transition metal oxides are known for their diverse and strongly correlated electronic phases, such as high-temperature superconductivity, ferromagnetism, antiferromagnetism, and charge density waves. These properties are highly dependent on precise lattice structures and electron configurations, making the accurate design and growth of these materials critical for unlocking their full potential. However, stabilizing artificially engineered metastable states in these materials has long posed a significant challenge.

Traditional growth methods like oxide molecular beam epitaxy (OMBE) and pulsed laser deposition (PLD) each offer distinct benefits. OMBE enables atomic-scale layer-by-layer growth with precise stoichiometric control but is restricted to low-pressure environments due to the vapor pressure of the evaporated materials, limiting its oxidation capacity. In contrast, PLD offers greater pressure tolerance, versatility, and cost efficiency but struggles with precise stoichiometry control and the growth of complex, large-unit-cell structures.

Addressing these challenges, researchers at the Laboratory of Superconductivity Mechanism at the Department of Physics, Southern University of Science and Technology (SUSTech), along with the Quantum Science Center of the Guangdong-Hong Kong-Macao Greater Bay Area (QSC-GBA), have developed a novel technique called Gigantic-Oxidative Atomic-Layer-by-Layer Epitaxy (GOALL-Epitaxy). This approach combines the precision of OMBE with the oxidative power of PLD, achieving three to four orders of magnitude higher oxidation power, making it ideal for fabricating complex materials requiring intense oxidative environments.

GOALL-Epitaxy utilizes a liquefaction-purified ozone source injected directly onto the substrate surface at high concentration and flow rate through a specially designed nozzle. This setup ensures rapid, sustained oxidation under high temperatures, critical for the precise growth of complex oxide structures. Additionally, the technique leverages high-energy laser pulses to ablate single-element oxide targets, facilitating higher growth pressures while maintaining atomic-layer precision.

In recent experiments, the team successfully fabricated various complex nickelates and cuprates, including a custom-designed nickelate structure featuring alternating single and double NiO2 layers, a foundational structure for high-temperature superconductivity. This breakthrough underscores the potential of GOALL-Epitaxy to expand the discovery of new high-temperature superconductors and other strongly correlated electronic systems, pushing the boundaries of material science.

Research Report:Gigantic-oxidative atomic-layer-by-layer epitaxy for artificially designed complex oxides