Dirac point movement and topological phase transition in patterned graphene.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Graphene's honeycomb lattice features Dirac cones with linear dispersion and pseudospin chirality.
• Lattice anisotropy can move Dirac points, potentially inducing topological transitions from semimetal to semiconductor.
• Achieving significant Dirac point movement typically requires impractically high lattice anisotropy.

Purpose of the Study:

• To investigate methods for inducing Dirac point drift in graphene.
• To explore the possibility of achieving topological phase transitions in graphene through controlled structural modifications.
• To analytically predict and computationally verify Dirac point movement and associated phase transitions.

Main Methods:

• Introducing anisotropic defects to break graphene's C3 symmetry.
• Utilizing periodic patterning to induce intervalley scattering.
• Analytical prediction of Dirac point drift.
• First-principles electronic structure calculations for verification.

Main Results:

• Anisotropic defects cause Dirac point drift in the Brillouin zone.
• Periodic patterning induces intervalley scattering, leading to a semimetal-to-insulator topological phase transition.
• Analytical predictions for Dirac point drift magnitude and direction align with computational results.

Conclusions:

• Periodically patterned graphene provides a viable platform for studying Dirac point movement.
• This approach facilitates research into topological phase transitions driven by Dirac point dynamics.
• The findings offer new avenues for manipulating graphene's electronic properties.