Theorie-Kolloquium Efremov

Superconductivity from repulsive interaction

In this talk I will discuss Cooper pairing in Fermi systems with repulsive interaction. I will
show that in the limit of the weakly coupled Fermi gas, the so-called Kohn-Luttinger mechanism gives an effective attraction, and consequently the Cooper instability. Then the transformation of the Kohn-Luttinger mechanism to the spin-fluctuation mechanism in multiband systems, such as Fe-based superconductors and transition metal dichalcogenides, will be considered. Interplay of the spin and charge degrees of freedom will be examined. Finally, I will discuss the experimental situation in Fe-based superconductors.