Transmission and absorption of electromagnetic waves in biased tetragonal Germanene: effects of electronic interaction and magnetic field

We calculate the optical absorption rate, refractive index, and absorption coefficient of the tetragonal Germanene layer under the influence of bias voltage and a transverse magnetic field. To explore local Coulomb interactions among the electrons, we apply the Hubbard model Hamiltonian to determine the electronic density of states. Our analysis focuses on the impact of bias voltage, Hubbard parameter, and transverse magnetic field strength on the frequency-dependent optical absorption and refractive index of tetragonal Germanene. Utilizing linear response theory and Green’s function approach, we derive the frequency behavior of these optical properties. Furthermore, we study the transmissivity and reflectivity of electromagnetic waves at normal incidence when interacting with a tetragonal Germanene layer positioned between two dielectric media. Our numerical results reveal that the frequency-dependent optical absorption exhibits a peak in the presence of both magnetic fields and bias voltage. Additionally, we observe the presence of Drude weight at very low frequencies in the optical absorption of the tetragonal Germanene monolayer.