Engineering Symmetry Breaking Interfaces by Nanoscale Structural-Energetics in Orthorhombic Perovskite Thin Films

Area of Science:

• Materials Science
• Solid-State Physics
• Crystallography

Background:

• Atomic configuration and interfaces are crucial for designing advanced materials.
• Understanding the interplay of strain and connectivity in thin films is key for controlling material properties.

Purpose of the Study:

• To investigate the formation and characteristics of a novel interface in transition metal oxide films.
• To understand how competing energetic factors influence film orientation and structure.

Main Methods:

• Atomic-resolution scanning transmission electron microscopy (STEM) was used to analyze the film's atomic structure.
• Second-principles atomistic modeling was employed to simulate interface formation and energetics.

Main Results:

• A 90° orientation switch was observed within the LaVO3 film, forming an internal "switching plane" instead of at the film-substrate interface.
• This internal interface couples mismatched oxygen octahedra rotations by minimizing distortions on either side.
• The switching plane breaks inversion symmetry and joins regions with different mechanical strain states.

Conclusions:

• The formation of this energetic internal interface is dependent on film thickness and requires structural relaxation.
• This discovery enables the creation of interfaces between otherwise immiscible phases within a single material.
• The findings open new avenues for nanoscale engineering of functional heterostructures, such as magnetic materials.