https://doi.org/10.1140/epjb/e2017-80477-8
Regular Article
Strong temperature effect on the sizes of the Cooper pairs in a two-band superconductor
1
Institute of Physics, University of Tartu,
W. Ostwaldi Str. 1,
50411
Tartu, Estonia
2
Department of Theoretical Physics, The Royal Institute of Technology,
10691
Stockholm, Sweden
3
Lublin University of Technology, Faculty of Mechanical Engineering,
Nadbystrzycka 36,
20618
Lublin, Poland
4
AGH University of Science and Technology, Department of Process Control,
Mickiewicza 30,
30-059
Krakow, Poland
a e-mail: teet.ord@ut.ee
Received:
17
August
2017
Received in final form:
9
November
2017
Published online: 15
January
2018
We study the temperature dependencies of the mean sizes of the Cooper pairs in a two-band BCS-type s-wave superconductivity model with coupling cut-off in the momentum space. It is found that, in contrast to single-band systems, the size of Cooper pairs in the weaker superconductivity band can significantly decrease with a temperature increase due to an interband proximity effect. The relevant spatial behaviour of the wave functions of the Cooper pairs is analyzed. The results also indicate a possibility that the size of Cooper pairs in two-band systems may increase with an increase in temperature.
Key words: Solid State and Materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2018