3D oxygen vacancy distribution and defect-property relations in an oxide heterostructure

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Oxide heterostructures display diverse physical properties, including unconventional superconductivity and topological polar order.
• Oxygen content variations significantly influence electronic correlation phenomena in oxides, but quantifying their impact is challenging.

Purpose of the Study:

• To quantify the distribution of oxygen vacancies in multiferroic (LuFeO3)9/(LuFe2O4)1 superlattices.
• To correlate oxygen vacancy distribution with electric and magnetic properties.
• To establish a 3D, atomic-scale approach for defect quantification in oxide heterostructures.

Main Methods:

• Atom probe tomography was employed to measure chemical composition and map oxygen vacancy distribution.
• Analysis focused on correlating 3D vacancy arrangements with ferroelectric and ferrimagnetic properties.

Main Results:

• Oxygen vacancies were observed to form a layered 3D structure with a local density of ~10^14 cm^-2.
• Vacancy ordering aligns with ferrimagnetic LuFe2O4 layers, driven by reduced local formation energy.
• Oxygen vacancies play a critical role in stabilizing ferroelectric domains in LuFeO3 and ferrimagnetism in LuFe2O4.

Conclusions:

• Pronounced interactions exist between oxygen vacancies and multiferroic order in the studied superlattices.
• The developed method allows for precise 3D quantification of oxygen defects.
• This provides new avenues for controlling properties in oxide heterostructures through defect engineering.