Two-band calculations on the upper critical field of superconductor NbSe2

Based on two-band Ginzburg–Landau theory, we study the temperature dependence of upper critical field for superconducting crystal NbSe2. The results reproduce the experimental data in a broad temperature range, especially the upward curvature near the transition temperature. Our calculations also indicate that in NbSe2 the band with the smaller gap is almost isotropic, and most probably located on the bonding Nb Fermi sheets.

► We study the temperature dependence of upper critical field for NbSe2. ► Temperature dependence of the anisotropy parameter is also determined. ► The band with the smaller gap is most probably located on the bonding Nb Fermi sheet.