Unique electronic and optical properties of ABBA tetralayer graphene under external electric fields

In this study, we examine the electronic and optical properties of ABBA-stacked tetralayer graphene (4LG), emphasizing its unique characteristics in contrast to its counterparts. The full tight-binding model elucidates the significance of interlayer couplings in the system. We investigate the influence of gate voltage on the system and uncover alterations in the band structure, the emergence of edge states, and the formation of band gaps. The analysis of the density of states reveals the existence of van Hove singularities, which dynamically evolve with the changing gate voltage, resulting in a transition from semimetallic to semiconductor properties. The optical absorption spectrum demonstrates asymmetrical peaks and step-like structures, further affected by a potential difference. Under a finite electric field, optical excitations in gated 4LG reveal triangular isoenergy loops with significant interaction-induced distortions of up to 100 meV. This study anticipates the potential for tuning optical properties in ABBA-stacked 4LG through external electric fields, offering opportunities for experimental exploration.