Correlation-Driven Dimerization and Topological Gap Opening in Isotropically Strained Graphene

Area of Science:

• Materials Science
• Condensed Matter Physics
• Quantum Chemistry

Background:

• Previous models of strained graphene phase diagrams were incomplete.
• Ignoring electron correlations, mobile carbons, or stress effects leads to inaccurate predictions.

Purpose of the Study:

• To accurately calculate the ground state enthalpy of strained graphene.
• To investigate the phase transitions and electronic properties of strained graphene.

Main Methods:

• Utilizing an off-lattice quantum Monte Carlo correlated ansatz for accurate enthalpy calculations.
• Performing parallel density-functional calculations for comparison.

Main Results:

• A semimetallic state at low strain transitions to a Kekulé-like dimerized (DIM) insulating state between 8.5% and 15% strain.
• The DIM state, stabilized by Heitler-London correlations, is a topological insulator with a predicted band gap exceeding 1 eV.
• This DIM state prevails over competing antiferromagnetic insulating states.

Conclusions:

• Electron correlations and applied stress are crucial for predicting graphene's phase diagram.
• Strained graphene can become a topological insulator with potential for 1D metallic interface states.
• The findings offer insights into the behavior of stressed 2D materials.