(001) SrTiO3 | (001) MgO interface and oxygen-vacancy stability from first-principles calculations

Area of Science:

• Materials Science
• Solid State Physics
• Surface Science

Background:

• Designing heterointerfaces with specific functionalities requires a deep understanding of their atomistic structures.
• Strontium titanate (SrTiO3) and magnesium oxide (MgO) are technologically relevant materials for oxide electronics.

Purpose of the Study:

• To investigate and characterize the stable interfacial structure of (001) SrTiO3 | (001) MgO.
• To explore the role of interfacial strain in the stabilization of oxygen vacancies at the heterointerface.

Main Methods:

• Density functional theory (DFT) calculations were employed to model and analyze the interfacial structures.
• Equation-of-state analysis was used to understand the stability of oxygen vacancies under different strain conditions.

Main Results:

• The TiO2-terminated SrTiO3 interface with MgO is identified as the most stable configuration due to favorable Mg-O and Ti-O electrostatic interactions.
• Oxygen vacancies are preferentially stabilized in regions of tensile strain at the interface.
• Conversely, oxygen vacancies are unstable under compressive strain, as confirmed by volume expansion analysis.

Conclusions:

• The study elucidates the atomic-level mechanisms governing the stability of the SrTiO3/MgO heterointerface.
• Controlling interfacial strain offers a pathway to manipulate oxygen vacancy concentration and thus tailor interface properties for advanced applications.