Two-dimensional transition-metal halide CoBr₃ with spin-polarized Dirac cone

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Two-dimensional (2D) transition-metal materials with unique magnetic and electronic properties are of significant interest for nanotechnology.
• Investigating novel 2D materials is crucial for advancing spintronics and nanoelectronics.

Purpose of the Study:

• To investigate the potential of the Cobalt Tribromide (CoBr3) monolayer for hosting a quantum anomalous Hall insulating phase.
• To determine the magnetic, electronic, and topological properties of the CoBr3 monolayer.

Main Methods:

• First-principles calculations were employed to study the electronic structure.
• Monte Carlo simulations were used to predict the Curie temperature (Tc).
• Phonon spectra analysis was performed to assess dynamic stability.
• Spin-orbit coupling was incorporated to analyze topological properties.

Main Results:

• The CoBr3 monolayer was identified as an intrinsic 2D ferromagnetic material with a predicted Curie temperature of 264 K.
• Phonon spectra confirmed the dynamic stability of the CoBr3 monolayer.
• Including spin-orbit coupling revealed a topologically non-trivial electronic structure with a global band gap of 8.7 meV.
• Anomalous Hall conductivity calculations yielded a Chern number (C) of 2, indicating two edge states in finite-width nanoribbons.

Conclusions:

• The CoBr3 monolayer is a promising candidate for a quantum anomalous Hall insulator.
• This discovery adds a new, experimentally feasible material to the quantum anomalous Hall insulator family.
• The findings suggest significant potential applications in nanoelectronics and spintronics.