Regensburg 2013 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

PV: Plenarvorträge

PV V

PV V: Prize Talk

Tuesday, March 12, 2013, 13:15–13:45, H1

Critical Quasi-particles and Scaling of Metals Near a Quantum Critical Point: a Strong Coupling Scenario. — •Peter Woelfle — ITKM and INT, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany --- Laureate of the Gentner-Kastler-Prize

A phenomenological theory of the critical properties of metals near a quantum critical point (QCP) governed by critical bosonic fluctuations at small momentum is presented. Assuming critical behavior of the electron quasi-particles (qp) all over the Fermi surface, as seen in a diverging effective mass m*, we determine the induced modification of the bosonic excitation spectrum. We use that the concept of electron qps is well-defined as long as the qp width is less than their excitation energy, which is still the case in the so-called non-Fermi liquid regime. In case that the interaction of the bosonic fluctuations is still weak, while the boson-qp interaction is strong, a controlled theory leads to a self-consistent equation for m*, with two physical solutions: the usual weak coupling solution and a strong coupling solution featuring a power law divergence of m* as a function of energy scale. We apply the theory to the antiferromagnetic (AFM) quantum phase transition observed in heavy fermion compounds (critical energy fluctuations), finding good agreement with data for YbRh2Si2 [1,2] and CeCu(6-x)Au(x). [1] P. Wölfle, and E. Abrahams, PR B 84, 041101 (2011); Ann. Phys. (Berlin) 523, 591 (2011); PR B 80, 235112 (2009). [2] E. Abrahams and P. Wölfle, PNAS 109, 3228 (2012). [3] E. Abrahams, J. Schmalian, and P. Wölfle, to be publ.