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TT: Fachverband Tiefe Temperaturen

TT 95: Cold Atomic Gases, Superfluids, Quantum Fluids and Solids

TT 95.9: Talk

Thursday, March 15, 2018, 17:15–17:30, HFT-FT 131

Out-of-bounds hydrodynamics in anisotropic Dirac fluids — Julia M. Link¹, Boris N. Narozhny^1,2, •Egor I. Kiselev¹, and Jörg Schmalian^1,3 — ¹Institute for Theory of Condensed Matter, Karlsruhe Institute of Technology, Karlsruhe, Germany — ²National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow, Russia — ³Insitute for Solid State Physics, Karlsruhe Institute of Thechnology (KIT), Karlsruhe, Germany

We study the hydrodynamic transport in an interacting electronic system with an anisotropic dispersion, which is Dirac-like along one crystallographic direction and Newtonian-like along the other. Such a dispersion is realized in systems with merging Dirac points at charge neutrality and leads to highly anisotropic transport coefficients. The shear viscosity is a fourth-rank tensor whose distinct elements characterize the momentum flow in different directions and exhibit fundamentally different scalings with temperature. One of the viscosity coefficients violates the lower bound for the shear viscosity to entropy density ratio stemming from the AdS/CFT duality.