Fermionic two-loop functional renormalization group for correlated fermions: Method and application to the attractive Hubbard model

Article

关键词: COHERENCE LENGTH SUPERCONDUCTORS;    MEAN-FIELD THEORY;    SPIN GAP;    SELF-CONSISTENT;    GROUP FLOWS;    SYSTEMS;    QUANTUM;    SYMMETRY;    BEHAVIOR;    LATTICE;   

DOI  :  10.1103/PhysRevB.90.115125

来源: SCIE

【 摘 要 】

We derive an efficient method for treating renormalization contributions at two-loop level within the functional renormalization group in the one-particle irreducible formalism for fermions. It is based on a decomposition of the two-particle vertex in charge, magnetic and pairing channels. The method treats single-particle and collective excitations in all channels on equal footing, allows for the description of symmetry breaking and captures collective mode fluctuation physics in the infrared. As a first application, we study the superfluid ground state of the two-dimensional attractive Hubbard model. We obtain superfluid gaps that are reduced by fluctuations in comparison to the one-loop approximation and demonstrate that the method captures the renormalization of the amplitude mode by long-range phase fluctuations.

【 授权许可】

Free