Estados eletrônicos de nanofitas de redes de Lieb, transição e Kagome

Abstract

Since the isolation of graphene in 2004, the scientific community has been looking for new two-dimensional (2D) materials aiming at different technological applications. It is known that the chemical components involved, the type of hybridization and the geometry formed are key factors for the resulting electronic band structure. This led to a theoretical investigation into possible designed crystals with desired geometries and interesting physical properties. Examples of 2D materials engineering are the Lieb and Kagome lattices, in which their band structures are formed by the coexistence of a conical Dirac energy band and a flat (non-dispersive) band. Such configurations have motivated research on electronic lattices, waveguides-based photonic systems, and even organic structures with these lattices’ periodicity. Motivated by the growing interest in these lattices and inspired by studies that explore the finite size effects on the electronic spectrum of graphene, we systematically investigate the electronic properties of nanoribbons of monolayer Lieb, transition and Kagome, using the tight-binding model, with a general Hamiltonian that describes both lattices. Results for the energy spectrum, density of states, and wave functions are discussed for nanoribbons with three types of edges: straight, bearded and asymmetrical. Effects of sublattice symmetry breaking induced in nine different nonequivalent ways are investigated for the infinite-sheet structures of these lattices and for the different configurations of the nanoribbons. We also explore the degeneracy of the quasi-flat states with respect to the nanoribbon width and due to the inclusion of the second-neighbor effect in the tight-binding model.