Graphene analogue in (111)-oriented BaBiO₃ bilayer heterostructures for topological electronics

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Topological electronics leverages topological charges for current conduction.
• Graphene-like structures are ideal for topological electronics due to Dirac cones and Berry phases.
• Tunable mass gaps and spin-orbit coupling are crucial for realizing diverse topological phases.

Purpose of the Study:

• To propose a novel material system for topological electronics applications.
• To demonstrate a tunable graphene analogue using a (111)-oriented BaBiO3 bilayer (BBL) heterostructure.
• To explore the realization of quantum spin Hall (QSH) and quantum valley Hall (QVH) phases in BBL.

Main Methods:

• Theoretical proposal of a BBL heterostructure sandwiched between large-gap perovskite oxides.
• Investigation of the role of neighboring perovskite spacers in controlling inversion symmetry.
• Analysis of topological phase transitions (QSH and QVH) based on symmetry breaking.

Main Results:

• The BBL heterostructure acts as a tunable graphene analogue with controllable topological phases.
• Conserved inversion symmetry leads to the quantum spin Hall (QSH) phase.
• Broken inversion symmetry results in the quantum valley Hall (QVH) phase, with tunable phase switching possible using ferroelectric spacers.

Conclusions:

• The proposed BBL heterostructure is a promising candidate for topological electronics.
• The ability to switch between QSH and QVH phases allows for the generation of topological domain boundaries.
• BBL serves as a versatile building block for complex oxide heterostructures in topological applications.