Helical Superconducting Black Holes

103

We construct anisotropic black brane solutions and analyse the behaviour of some of their metric perturbations. These solutions correspond to field theory duals in which rotational symmetry is broken due an externally applied, spatially constant, force. We find, in several examples, that when the anisotropy is sufficiently big compared to the temperature, some components of the viscosity tensor can become very small in units of the entropy density, parametrically violating the KSS bound. We obtain an expression relating these components of the viscosity, in units of the entropy density, to a ratio of metric components at the horizon of the black brane. This relation is generally valid, as long as the forcing function is translationally invariant, and it directly connects the parametric violation of the bound to the anisotropy in the metric at the horizon. Our results suggest the possibility that such small components of the viscosity tensor might also arise in anisotropic strongly coupled fluids found in nature.

Section: Jhep10(2015)028mentioning

confidence: 99%

The shear viscosity in anisotropic phases

Jain

Samanta

Trivedi

2015

103

“…5 Spatially modulated phases such as charge density wave (CDW) phase and checkerboard structure in high-temperature superconductors are associated with spontaneously breaking spatially translational invariance. There are some studies of the spontaneous breaking of translational invariance in variety of holographic theories [54][55][56][57][58][59][60][61][62][63][64][65]. The corresponding broken solutions could be related to the spatially modulated phases of condensed matter systems in which, for example, superconducting order can compete or coexist with CDWs or checkerboard orders in the pseudogap region.…”

Section: Gravity Dual Of Broken Phasesmentioning

confidence: 99%

Holographic competition of phases and superconductivity

Kiritsis

2016

We use a holographic theory to model and study the competition of four phases: an antiferromagnetic phase, a superconducting phase, a metallic phase and a striped phase, using as control parameters temperature and a doping-like parameter. We analyse the various instabilities and determine the possible phases. One class of phase diagrams, that we analyse in detail, is similar to that of high-temperature superconductors as well as other strange metal materials.

“…There have been interesting holographic studies of some such spatially modulated phases -notably, studies of emergent helical order [22][23][24][25][26][27][28][29][30], stripe order [31][32][33][34][35][36], and more elaborate orders [37][38][39][40]. One largely open problem is to give simple analytical examples of phases realizing or even combining the various properties mentioned above (e.g.…”

Section: Introductionmentioning

confidence: 99%

Extremal horizons with reduced symmetry: hyperscaling violation, stripes, and a classification for the homogeneous case

Iizuka

Kachru

Kundu

et al. 2013

Classifying the zero-temperature ground states of quantum field theories with finite charge density is a very interesting problem. Via holography, this problem is mapped to the classification of extremal charged black brane geometries with anti-de Sitter asymptotics. In a recent paper [1], we proposed a Bianchi classification of the extremal nearhorizon geometries in five dimensions, in the case where they are homogeneous but, in general, anisotropic. Here, we extend our study in two directions: we show that Bianchi attractors can lead to new phases, and generalize the classification of homogeneous phases in a way suggested by holography. In the first direction, we show that hyperscaling violation can naturally be incorporated into the Bianchi horizons. We also find analytical examples of "striped" horizons. In the second direction, we propose a more complete classification of homogeneous horizon geometries where the natural mathematics involves real four-algebras with three dimensional sub-algebras. This gives rise to a richer set of possible near-horizon geometries, where the holographic radial direction is non-trivially intertwined with field theory spatial coordinates. We find examples of several of the new types in systems consisting of reasonably simple matter sectors coupled to gravity, while arguing that others are forbidden by the Null Energy Condition. Extremal horizons in four dimensions governed by three-algebras or four-algebras are also discussed.