arXiv subjects

Elisa Serrano Richaud

Publications and source records attributed to Elisa Serrano Richaud.

3 recordsLinked to original sources

arXiv2026

First-principle investigation of the electronic structure and optical properties of graphene/boron nitride lateral heterostructures

We investigate the electronic and optical properties of lateral heterostructures made of alternated armchair ribbons of graphene and hexagonal boron nitride. It is known that the gapwidth of these heterostructures can be classified into three families depending on the width of the graphene part. Here, by employing ab initio methods (standard and time-dependent density functional theory and GW), we demonstrate that such classification still holds for other electronic states close to the gap. We show that they display trends substantially different from those known for the gapwidth and originate family-specific features in the screening properties and optical absorption spectra (peak energy and intensity). In addition, our use of a tight binding model originally introduced for isolated nanoribbons allows us to discuss some crucial heterostructure's properties in view of those of its isolated building blocks, including charge redistribution at the edges, gap hierarchy inversion, and specific optical selection rules. By bridging the electronic structure to optical absorption spectra in a comprehensive set of systems, this study sets the stage for more refined investigations on the absorption properties of graphene/boron nitride lateral heterostructures.

cond-mat.mtrl-sci↗

arXiv2024

Gap engineering and wave function symmetry in C and BN armchair nanoribbons

Many are the ways of engineering the band gap of nanoribbons including application of stress, electric field and functionalization of the edges. In this article, we investigate separately the effects of these methods on armchair graphene and boron nitride nanoribbons. By means of density functional theory calculations, we show that, despite their similar structure, the two materials respond in opposite ways to these stimuli. By treating them as perturbations of a heteroatomic ladder model based on the tight-binding formalism, we connect the two behaviours to the different symmetries of the top valence and bottom conduction wave functions. These results indicate that opposite and complementary strategies are preferable to engineer the gapwidth of armchair graphene and boron nitride nanoribbons.

cond-mat.mes-hall↗

arXiv2024

Emergence of flat bands in the quasicrystal limit of boron nitride twisted bilayers

We investigate the electronic structure and the optical absorption onset of close-to-30\degree twisted hexagonal boron nitride bilayers. Our study is carried out with a purposely developed tight-binding model validated against DFT simulations. We demonstrate that approaching 30\degree (quasicrystal limit), all bilayers sharing the same moiré supercell develop identical band structures, irrespective of their stacking sequence. This band structure features a bundle of flat bands laying slightly above the bottom conduction state which is responsible for an intense peak at the onset of the absorption spectrum. These results suggest the presence of strong, stable and stacking-independent excitons in boron nitride 30\degree-twisted bilayers. By carefully analyzing the electronic structure and its spatial distribution, we elucidate the origin of these states as moiré-induced K-valley scattering due to interlayer B$-$B coupling. We take advantage of the the physical transparency of the tight-binding parameters to derive a simple triangular model based on the B sublattice that accurately describes the emergence of the bundle. Being our conclusions very general, we predict that a similar bundle should emerge in other close-to-30{\degree} bilayers, like transition metal dichalcogenides, shedding new light on the unique potential of 2D materials.

cond-mat.mtrl-sci↗