Tunable field-dependent electronic and thermal conductivity of tetragonal germanene nanoribbons under temperature,...

This theoretical study investigates the properties of T-GeNRs using tight-binding formalism, Green's function, and the Kubo formula. Our research examines the temperature dependence of thermodynamic functions under varying external parameters, including electric bias and magnetic fields and chemical potential. The application of bias voltage induces a band gap, the magnetic field enhances the density of states (DOS) and the chemical potential modulates the charge carrier concentration, leading to distinct modifications in the electrical and thermal properties across different temperature ranges. The electrical property analysis reveals that the unperturbed structure exhibits metallic behavior. This feature remains unchanged under magnetic field, with increasing field strength leading to significant enhancing DOS spectrum intensity. In contrast, the introduction of voltage bias induces a metal-to-semiconductor transition, with the band gap size being directly correlated to the bias strength. The thermodynamic properties, including electrical and thermal conductivity, Magnetic susceptibility and the Lorenz number, demonstrate distinct responses to external fields, while bias voltage reduces these properties, the magnetic field enhances them. A particularly notable feature in the temperature dependence of thermodynamic functions is emergence a zero-intensity region attributed to the energy gap formation. The occurrence of this zero-intensity temperature region is closely related to field strength, increasing with bias voltage and decreasing with the magnetic field. To optimize thermodynamic performance in the selected structures, the simultaneous application of voltage bias and a magnetic field can be employed, making T-GeNRs promising candidates for nanoelectronic and thermophotonic applications.