First-principles study of superconducting transition temperature of niobium and vanadium as a function of pressure

Abstract

Ultra-high pressure has recently led to the observation of high Tc superconductors. The exploration of superconducting properties under high pressure conditions offers valuable insights into the fundamental mechanisms governing superconductivity and opens avenues for the synthesis of novel materials with enhanced superconducting properties. In this study, the superconducting transition temperature, Tc, for niobium and vanadium has been investigated to maximum pressures of 250.0 and 70.0 GPa, respectively. Density functional theory and density functional perturbation theory were used to undertake first-principles computations to investigate the variations of superconducting properties under pressure. For both the metals niobium (Nb) and vanadium (V), we observed that the density of states at the Fermi level decreased, while the overall phonon frequency generally increased with pressure. For Nb, we find that the electron–phonon coupling constant (λ) and the superconducting transition temperature (Tc) decrease steadily with pressure; however, for V, we find that λ and Tc decrease smoothly up to 26.0 GPa, and then gradually increase to 70.0 GPa pressure. The observed phonon spectrum nature for both Nb and V is in good agreement with the neutron scattering approach’s output.