Self-energy effects in functional renormalization group flows of the two-dimensional $t$-$t'$ Hubbard model away from van Hove filling

Abstract

We study the impact of the fermionic self-energy on one-loop functional renormalization group flows of the two-dimensional $t$-$t'$ Hubbard model, with emphasis on electronic densities away from van Hove filling. In the presence of antiferromagnetic hot spots, antiferromagnetic fluctuations lead to a flattening of the Fermi surface, shift magnetic phase boundaries and significantly enhance critical scales. We trace back this effect to the presence of a magnetic first order transition. For some parameters, the first order character of the latter is reduced by self-energy effects. For reliably determining phase diagrams, the fermionic self-energy should thus be taken into account in functional renormalization group studies if scattering between hot spots is important.