Effects of scattering on the field-induced Tc enhancement in thin superconducting films in a parallel magnetic field

The problem of the normal-superconducting phase boundary for films in a parallel magnetic field, discussed in the classical paper by Ginzburg and Landau for temperatures close to the critical, is revisited with the help of the microscopic BCS theory for arbitrary temperatures taking pair-breaking and transport scattering into account. Although confirming experimental findings of the Tc enhancement by the magnetic field, we find that the transport scattering pushes the phase transition curve to higher fields and higher temperatures for nearly all practical scattering rates. Still, the Tc enhancement disappears in the dirty limit. We also consider intriguing changes, such as reentrant superconductivity, caused to the phase boundary by pair-breaking magnetic ions spread on one of the film faces. These features await experimental verification.

Automated summary

In this article, the problem of the normal-superconducting phase boundary for films in a parallel magnetic field is revisited using the microscopic BCS theory, considering pair-breaking and transport scattering at arbitrary temperatures. The study confirms that the magnetic field enhances the critical temperature (Tc), but the presence of transport scattering shifts the phase transition curve to higher fields and temperatures. However, in the dirty limit, the enhancement of Tc disappears. The article also discusses intriguing changes to the phase boundary caused by pair-breaking magnetic ions on the film, such as reentrant superconductivity, which require experimental verification.