Rydberg Excitons in buckled two-dimensional materials in presence of parallel magnetic and electric fields*

We study direct and indirect magnetoexcitons Rydberg states in monolayers and double-layer heterostructure of Xenes: silicene, germanene, and stanene, encapsulated by h-BN. The monolayers and heterostructures are in external parallel magnetic and electric fields, which are perpendicular to the structure. We calculate binding energies of magnetoexcitons for the Rydberg states 1s, 2s, 3s, and 4s by a solution of the Schrödinger equation using both the Rytova-Keldysh and Coulomb potentials for the description of electron-hole interaction. This allows to understand a role of screening in Xenes. In the external perpendicular electric field, the buckled structure of the Xene monolayers leads to appearance of potential difference between sublattices allowing to tune electron and hole masses and, therefore, the binding energies of magnetoexcitons. We report the energy contribution from magnetic and electric fields to the binding energies and diamagnetic coefficients. The tunability of magnetoexciton properties by parallel magnetic and electric fields is demonstrated. The calculations of the binding energies and diamagnetic coefficients of magnetoexcitons in Xenes monolayers and heterostructure are novel.