Self-consistent two-gap description of MgB2 superconductor

Abstract

A self-consistent two-gap γ-model is used to quantitatively describe several thermodynamic properties of MgB2 superconductor. The superconducting coupling matrix, vij, was obtained from the fitting of the superfluid density in the entire superconducting temperature range. Using this input, temperature-dependent superconducting gaps, specific heat, and upper critical fields were calculated with no adjustable parameters and compared with the experimental data as well as with the first-principles calculations. The observed agreement between fit and data shows that γ-model provides adequate quantitative description of the two-gap superconductivity in MgB2 and may serve as a relatively simple and versatile self-consistent description of the thermodynamic quantities in multi-gap superconductors.