Selenium-based hetero-circulene monolayer: Coexistence of gapped Dirac fermions, heavy fermions and semiconductivity in a single quantum platform with lithium-ion battery applications

Abstract

Semiconductivity, Dirac fermions, and correlated heavy fermions typically emerge in distinct material classes, such as transition metal dichalcogenides, graphene, and magic-angle twisted bilayer graphene. Integrating all three quantum features into a single platform has long been a challenge. In this study, we introduce a two-dimensional selenium-based hetero-circulene (Se-HC) monolayer composed of a carbon–selenium framework and explore its properties using density functional theory. The Se-HC monolayer exhibits dynamical, thermal, and mechanical stability. Strikingly, its electronic structure reveals a rare coexistence of gapped Dirac fermions and heavy fermions, with linearly dispersive and flat bands near the Fermi level. The Dirac cones are isotropic, with a Fermi velocity of ∼1.94 × 105 m/s. A narrow direct band gap separates these states by 73 meV using PBE-GGA and 0.40 eV with HSE06, enabling semiconducting behaviour without sacrificing Dirac physics. The band gap is highly tuneable via mechanical strain, compressive strain increases it, while tensile strain reduces it. We also study quasi-one-dimensional derivatives, including nanoribbons and nanotubes, and assess potential of Se-HC as a lithium-ion battery anode. This integration of semiconducting, Dirac, and flat-band features positions Se-HC as a versatile platform for quantum materials, with promising implications for next-generation electronic and energy applications.

Keywords: DFT, Gapped Dirac fermions, Li-ion battery, Massive fermions, Two-dimensional materials Dirac materials.