Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 84: Correlated Electrons: (General) Theory

TT 84.10: Vortrag

Donnerstag, 3. April 2014, 12:00–12:15, HSZ 304

Fermionic functional renormalization group flows into antiferromagnetically ordered phases — •Stefan A. Maier and Carsten Honerkamp — Institute for Theoretical Solid State Physics, RWTH Aachen University, 52074 Aachen, Germany and JARA - FIT Fundamentals of Future Information Technology

In this talk, we report on purely fermionic functional renormalization group flows into antiferromagnetically ordered phases. Starting from the fRG one-loop flow equations, a hierarchy of approximations is devised. Interaction terms breaking the discrete time-reversal and translational symmetries are thereby successively neglected, whereas they remain broken on the one-particle level. In the course of these approximations, also an exchange parametrization is employed. For the spin-density wave (SDW) phase of a two-pocket model initially proposed by Chubukov et al. in Phys. Rev. B 78 134512, the flow equations are then integrated numerically at the most approximate level of the hierarchy. This yields a SDW gap that is significantly reduced compared to mean-field theory, and the inclusion of the charge-density wave and singlet-pairing channels turns out to be crucial. The observed violation of the SU(2) Ward identity appears acceptable on a qualitative level, suggesting that the underlying approximations are physically meaningful.