Synthesizing Two-Dimensional Chiral Cobalt Telluride through a Predesigned Buffer Layer

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• Two-dimensional (2D) chiral materials are crucial for enantioselective catalysis, spin-polarized optoelectronics, and quantum information technologies.
• Controllable and scalable synthesis of these 2D chiral systems remains a significant challenge.

Purpose of the Study:

• To demonstrate the epitaxial growth of 2D chiral cobalt telluride (CoTe₂) on an achiral gold (Au(111)) substrate.
• To elucidate the growth mechanism and chiral pattern formation in CoTe₂ monolayers.
• To establish a scalable pathway for fabricating tailored 2D chiral materials.

Main Methods:

• Epitaxial growth via molecular beam epitaxy (MBE).
• Surface characterization using scanning tunneling microscopy (STM).
• Theoretical analysis employing density functional theory (DFT) calculations.

Main Results:

• Formation of an Au₂Te buffer layer guiding CoTe₂ linear chain intermediate growth.
• Generation of a defective 1T-CoTe₂ monolayer with chiral pinwheel superlattice of Te vacancies.
• Healing of defects and formation of a complete 1T-CoTe₂ monolayer with spiral chiral patterns.
• Identification of a strain-mediated mechanism for chiral pattern formation.

Conclusions:

• Successfully demonstrated a scalable MBE approach for synthesizing 2D chiral CoTe₂ monolayers.
• Revealed the crucial role of Te vacancies and strain in achieving chiral structures.
• This work provides a pathway for designing and fabricating novel 2D chiral materials for advanced applications.