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TT: Fachverband Tiefe Temperaturen

TT 41: Correlated Electrons: Quantum-Critical Phenomena

TT 41.1: Vortrag

Mittwoch, 22. März 2017, 09:30–09:45, HSZ 204

Quantum criticality with a twist: interplay of strong correlations and Kohn anomalies in three dimensions — •Thomas Schäfer¹, Andrey A. Katanin², Karsten Held¹, and Alessandro Toschi¹ — ¹Institute of Solid State Physics, TU Wien, 1040 Vienna, Austria — ²Institute of Metal Physics, 620990, Kovalevskaya str. 18, Ekaterinburg, Russia; Ural Federal University, 620002, Mira str. 19, Ekaterinburg, Russia

Quantum critical points (QCPs) are among the most interesting phenomena in condensed matter systems and can emerge by exploiting a non-thermal parameter to suppress finite-temperature phase transitions. Although the limit of zero temperature cannot be reached experimentally, the existence of a QCP can severely influence the system’s excitation spectrum. In spite of the intrinsic interest, a consistent theory for QCPs has not been established yet, due to the associated intermingling of temporal and spatial correlations. In this talk, quantum critical properties of the fundamental model of electronic correlations, the Hubbard model in three dimensions, are studied by means of a diagrammatic extension of the dynamical mean field theory, the dynamical vertex approximation (DΓA). The model’s magnetic phase diagram is computed upon doping and its critical regions and exponents are analyzed. Quite unexpectedly, the quantum critical properties are found to be driven by the model’s Fermi surface properties (Kohn points), even in presence of strong correlations, contradicting the predictions of the conventional Hertz-Millis-Moriya theory.

[1] T. Schäfer et al., arXiv:1605.06355 (2016).