Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 25: Correlated Electrons: Quantum-Critical Phenomena 1

TT 25.6: Talk

Wednesday, March 28, 2012, 10:45–11:00, H 3010

Functional renormalization group approach to singular interactions in 2D metals — •Casper Drukier, Lorenz Bartosch, Aldo Isidori, and Peter Kopietz — Universität Frankfurt, Frankfurt am Main, Germany

Using functional renormalization group methods we study an effective low-energy model describing the breakdown of Fermi-liquid behaviour in two-dimensional metals when gapless fermions at the Fermi surface are coupled by a fluctuating bosonic order parameter.

Using a field-theoretical approach, Metlitski and Sachdev [Phys. Rev. B 82, 075127] have recently found that certain three-loop diagrams strongly modify the one-loop results, and that the conventional 1/N expansion breaks down in this problem. We show that the three-loop diagrams discovered by Metlitski and Sachdev are contained in a rather simple truncation of the functional renormalization group flow equations, containing only irreducible vertices with two and three legs. An approximate solution of these flow equations yields explicit expressions for the vertex corrections, and allows us to calculate the scale-dependent anomalous dimension beyond one-loop level.