2024/09/25 by Henheik, Joscha, Langmann, Edwin, Lauritsen, Asbjørn Bækgaard
#46N50 #81Q10 #82D55 #FOS: Physical sciences #Mathematical Physics (math-ph) #Quantum Gases (cond-mat.quant-gas) #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2409.17297
We introduce a multi-band BCS free energy functional and prove that for a multi-band superconductor the effect of inter-band coupling can only increase the critical temperature, irrespective of its attractive or repulsive nature and its strength. Further, for weak coupling and weaker inter-band coupling, we prove that the dependence of the increase in critical temperature on the inter-band coupling is (1) linear, if there are two or more equally strongly superconducting bands, or (2) quadratic, if there is only one dominating band.