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

TL;DR

This paper introduces GOALL-Epitaxy, a novel atomic-layer growth method with enhanced oxidation power, enabling precise synthesis of complex, metastable transition metal oxides for advanced material design.

Contribution

The paper presents a new epitaxy technique that significantly improves oxidation capability and atomic-layer control for complex oxides, expanding growth possibilities.

Findings

Successful growth of complex nickelates and cuprates.

Artificially designed layered structures with specific d-orbital occupancy.

Enhanced oxidation stability at high temperatures.

Abstract

In designing material functionalities for transition metal oxides, lattice structure and d-orbital occupancy are key determinants. However, the modulation of these two factors is inherently limited by the need to balance thermodynamic stability, growth kinetics, and stoichiometry precision, particularly for metastable phases. We introduce a methodology, namely the gigantic-oxidative atomic-layer-by-layer epitaxy (GOALL-Epitaxy), enhancing oxidation power 3-4 orders of magnitude beyond conventional pulsed laser deposition (PLD) and oxide molecular beam epitaxy (OMBE), while ensuring atomic-layer-by-layer growth of designed complex structures. Thermodynamic stability is markedly augmented with stronger oxidation at elevated temperatures, whereas growth kinetics is sustained by laser ablation at lower temperatures. We demonstrate the accurate growth of complex nickelates and cuprates, especially an artificially designed structure with alternating single and double NiO2 layers possessing distinct nominal d-orbital occupancy, as a parent of high-temperature superconductor. The GOALL-Epitaxy enables material discovery within the vastly broadened growth parameter space.