A DFT study on the role of excitons and electric field-induced symmetry breaking and topological properties of ZrBr

Abstract

The control of band gap and topological properties is a crucial objective in the field of materials science, particularly for the application of 2D materials such as topological insulators. Zirconium monobromide (ZrBr), a topological insulator with band inversion, holds significant potential for various applications. In this study, we used Density Functional Theory (DFT) with different approximations namely, Generalized Gradient Approximation (GGA) with and without spin orbit coupling (SOC) as well as hybrid functional to investigate the electronic structure and the band gap of this compound. In addition, we introduced the excitonic effect by considering GW plus Bethe–Salpeter equation (GW-BSE) to compute the optical band gap and quasi-particle energy. We found that ZrBr present a low static dielectric function and weak exciton binding energy, generally lower than those of conventional semiconductors. This behavior is due to the reduced Coulomb interaction in the material. To further explore the material’s behavior, we apply an electric field in three directions to observe symmetry breaking and its impact on band gap tuning. This comprehensive analysis aims to explore the understanding and the potential applications of ZrBr as a topological insulator.