Holographic Hydrodynamics of {\it Tilted} Dirac Materials

TL;DR

This paper develops a holographic model for tilted Dirac materials, revealing deviations in hydrodynamic properties such as reduced shear viscosity and KSS bound violation, which can be experimentally tested in specific 2D quantum materials.

Contribution

It introduces a gravity dual for tilted Dirac materials, providing new insights into their hydrodynamic behavior and deviations from normal Dirac fluids.

Findings

Shear viscosity to entropy density ratio is reduced.

KSS bound is violated in tilted Dirac materials.

Predictions applicable to specific 2D quantum materials.

Abstract

We present a gravity dual to a quantum material with tilted Dirac cone in 2+1 dimensional spacetime. In this many-body system the electronics degrees of freedom are strongly-coupled, constitute a Dirac fluid and admit an effective hydrodynamic description. The holographic techniques are applied to compute the thermodynamic variables and hydrodynamic transports of a fluid on the boundary of an asymptotically anti de Sitter spacetime with a boosted black hole in the bulk. We find that these materials exhibit deviations from the normal Dirac fluid which rely on the tilt of the Dirac cone. In particular, the shear viscosity to entropy density ratio is reduced and the KSS bound is violated in this system. This prediction can be experimentally verified in two-dimensional quantum materials ({\it e.g.} organic $\alpha$-({BEDT}-{TTF})$_2$I$_3$ and $8Pmmn$ borophene) with tilted Dirac cone.