Seminarium Fizyki Materii Skondensowanej

It is well known that antiferromagnetic fluctuations lead to unconventional superconductivity.In particular, they are believed to be a glue of high-temperature superconductivity in cupratesand iron pnictides. In this talk, in the framework of Eliashberg theory, I discuss thatthe spin-fluctuation mechanism suffers from the self-restraint effect of superconductivity in generaland is not favorable to realizing high-temperature superconductivity. I propose that the instantaneousspin interaction, instead of spin fluctuations, can be crucial to cuprate superconductors.I will also discuss briefly iron pnictides and other unconventional superconductorswith low critical temperatures.