Theoretical study on the two-band degenerate-gaps superconductors: Application to SrPt₃P

Highlights: • We study two-band degenerate-gaps superconductors with Ginzburg–Landau theory. • Exact solutions of upper critical field and London penetration depth are obtained. • The results directly underlie SrPt₃P is a multi-band degenerate-gaps superconductor. - Abstract: We study the magnetic properties of two-band degenerate-gaps superconductors with two-band isotropic Ginzburg–Landau theory. The exact solutions of upper critical field and London penetration depth are obtained, and the calculations reproduce the experimental data of the recently observed superconducting crystal SrPt₃P in a broad temperature range. It directly underlies that SrPt₃P is a multi-band superconductor with equal gaps in two Fermi surface sheets.