First-order normal-to-superconductor phase transition of aluminum in magnetic field by current-density functional theory for superconductors

Abstract

We demonstrate that the current-density functional theory for superconductors (sc-CDFT) can describe the magnetic-field-induced first-order phase transition of aluminum from a superconducting state to a normal state. This is accomplished by introducing a model for the magnetic-field dependence of the attractive interaction between superconducting electrons. This model states that the surface potential well produced by a penetrating magnetic field leads to the magnetic-field dependence of the attractive interaction. Specifically, the electron density near the surface increases with the magnetic field owing to the surface potential well, which causes a reduction in the attractive interaction because of the screening effect. We also develop a calculation scheme to solve the gap equation of the sc-CDFT by considering the magnetic-field dependence of the attractive interaction. The calculation results for the magnetic-field dependence of the superconducting gap are in good agreement with the experimental results of the first-order phase transition.