Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 50: Correlated Electrons: Quantum-Critical Phenomena - Theory

TT 50.7: Talk

Tuesday, April 1, 2014, 15:30–15:45, BEY 81

Heavy fermion quantum critical point from AdS/CFT correspondence — •Mihailo Čubrović — Institute for Theoretical Physics, University of Cologne, Germany

We propose a holographic (AdS/CFT) approach to strongly correlated electrons and study a quantum phase transition from small to large Fermi surface phase in a model "heavy fermion" system. AdS/CFT is a duality which maps the correlation functions from field theory to solutions of the equations of motion for classical fields in a curved spacetime, i.e. in general relativity. The appealing side of this approach is its nonperturbative nature: the calculations on the gravity side are essentially an expansion in inverse coupling strength and indeed work best in the strong coupling regime. We construct a gravity dual of a Fermi liquid system which shows a mass enhancement of the order of several hundred times the bare mass. At zero temperature, the system exhibits a continuous quantum phase transition to another Fermi liquid with different effective mass and Fermi momentum. The difference in sizes of the Fermi surfaces (i.e. Fermi momenta), as well as the fact that the transition happens at finite wavevector agree with the intuition on heavy fermion transitions. While the picture resembles the fractionalization scenario, we.do not introduce any emergent gauge fields. The shrinking of the Fermi surface can best be interpreted as formation of bound states between electrons and exotic bosonic excitations near the quantum critical point.