Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 48: Poster Session: Many Body Systems, Quantum Critical Phenomena

TT 48.5: Poster

Mittwoch, 18. März 2020, 15:00–19:00, P2/4OG

Hierarchy of energy scales in an antiferromagnetic quantum critical metal: a Monte Carlo study — •Carsten Bauer1, Yoni Schattner2, Simon Trebst1, and Erez Berg31University of Cologne, Germany — 2Stanford University, USA — 3The Weizmann Institute of Science, Israel

While quantum critical phenomena in insulators are fairly well understood, their metallic counterparts pose a substantial theoretical challenge since the order parameter fluctuations can interact with gapless excitations on a Fermi surface. When driving a metal through a phase transition, this interplay can lead to a damping of the critical modes and can give rise to unconventional superconductivity, and “strange metal” behavior. It might therefore serve as a microscopic model for some of the rich physics of high-Tc materials.

Fortunately, certain classes of metallic quantum critical points can be analyzed by determinant quantum Monte Carlo as one can circumvent the notorious “sign problem” and retain polynomial efficiency. I will show numerically exact studies of two dimensional metals at the verge of an antiferromagnetic transition indicating Landau-damping of the order parameter fluctuations and a breakdown of Fermi liquid theory. I will further discuss the case of an (almost) locally nested Fermi surface, where Tc is strongly suppressed. Lastly, I will demonstrate that a machine learning technique dubbed "quantum loop topography" can be utilized to probe transport and identify the superconductivity transition in such a many-particle system.

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