Colloquia

In my talk, I review recent and not so recent works aiming to understand whether a nominally repulsive Coulomb interaction can by itself give rise to a superconductivity.  I discuss a generic scenario of the pairing by electron-electron interaction, put forward by Kohn and Luttinger back in 1965, and  modern studies of  the electronic mechanisms of superconductivity in the lattice systems which model cuprates,  Fe-pnictides, and  doped graphene.  I show that the pairing in all three classes of materials can be viewed as a lattice version of Kohn-Luttinger physics, despite that the pairing symmetries are different.  I discuss under what conditions the pairing occurs and rationalize the need to do  renormalization-group studies.  I also discuss the interplay between superconductivity and density-wave instabilities.