Measurements of κ1(t) and κ2(t) in TaNb alloys

Magnetic behavior of dirty multiband superconductors near the upper critical field

“…It is possible however to develop a theory for κ 2 in superconductors with arbitrary impurity concentration 48,49 . In single-band superconductors κ 2 (T → 0) diverges in the clean limit but for experimentally relevant finite impurity concentrations the changes are not dramatic as compared to the dirty limit 51 . On the other hand in the multiband case an interplay between different Fermi velocities and impurity scattering rates should result in a non-trivial modifications of κ 2 (T ) temperature dependencies.…”

“…The theoretical calculations were found to be in good agreement with experimentally measured κ 2 (T ) dependencies in several superconducting alloys. [51][52][53] The parameter κ 2 is a basic quantity of type-II superconductors determining their thermodynamic 54 and transport properties 55,56 We consider multiband superconductors in a dirty limit using the Usadel theory 31 . Each k-th band is described in terms of the quasiclassical Green's function matrix ĝk = ĝk (ε, r) which is defined as follows…”