Spin bond order driven by extended repulsive interactions in doped graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Many-Body Theory

Background:

• Graphene's electronic properties near the van Hove singularity (VHS) are crucial for understanding its exotic behaviors.
• Correlated electron systems exhibit complex many-body instabilities that require advanced theoretical tools.

Purpose of the Study:

• Investigate many-body instabilities in graphene doped near the VHS.
• Determine the ground-state phase diagram and characterize emergent ordered phases.
• Explore the impact of Coulomb repulsions and screening on electronic instabilities.

Main Methods:

• Utilized the truncated-unity functional renormalization group (TUFRG) framework.
• Employed an extended Hubbard model with nearest-neighbor Coulomb repulsions.
• Applied a combined TUFRG + mean-field (MF) theory approach for detailed state description.

Main Results:

• Identified a spin-bond-order phase near the VHS, transitioning to a spin-density-wave phase with increased screening.
• Constructed the ground-state phase diagram based on doping level and screening parameter.
• Found collinear spin orders to be energetically favorable, with chirality emerging in the absence of third-nearest-neighbor hopping.

Conclusions:

• The study reveals novel spin-ordered phases in doped graphene near the VHS.
• TUFRG + MF scheme provides a powerful method for analyzing complex correlated electron systems.
• The metallic behavior persists in the identified spin-ordered states, offering potential for electronic applications.