Coupling Lattice Instabilities Across the Interface in Ultrathin Oxide Heterostructures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• Oxide heterointerfaces are crucial for novel electronic functionalities.
• Strong coupling between structural and electronic properties is observed in interfacing materials with different lattice symmetries.
• Strontium iridate (SrIrO3) is a topological crystalline metal with complex spin-orbit coupling and electronic correlations.

Purpose of the Study:

• To investigate the impact of cubic-tetragonal distortion in strontium titanate (SrTiO3) on the electronic properties of SrIrO3 thin films.
• To understand the structure-property relationships at oxide interfaces for potential applications in heterostructures.

Main Methods:

• Fabrication of SrIrO3 thin films on SrTiO3 substrates.
• Characterization of structural domain coupling below the SrTiO3 transition temperature (105 K).
• Measurement of electronic transport properties of the SrIrO3 films.

Main Results:

• Orthorhombic domains in SrIrO3 couple to tetragonal domains in SrTiO3 below 105 K.
• This coupling forces the in-phase rotational axis in-plane, creating a binary domain structure.
• Ultrathin SrIrO3 films exhibit strongly anisotropic transport properties due to reduced bandwidth along the in-phase axis, approaching a metal-insulator transition.

Conclusions:

• The study demonstrates a direct link between structural distortions and electronic anisotropy in SrIrO3/SrTiO3 heterostructures.
• Perovskite materials exhibit strong structure-property relationships suitable for interface coupling.
• This work provides a pathway for designing novel functionalities in oxide heterostructures through controlled interfacial coupling.