Under The Dome: Doped holographic superconductors with broken translational symmetry

We comment on a simple way to accommodate translational symmetry breaking into the recently proposed holographic model which features a superconducting dome-shaped region on the temperature-doping phase diagram.Comment: 14 pages, 6 figure

Phases of holographic superconductors with broken translational symmetry

We consider holographic superconductors in a broad class of massive gravity backgrounds. These theories provide a holographic description of a superconductor with broken translational symmetry. Such models exhibit a rich phase structure: depending on the values of the temperature and the disorder strength the boundary system can be in superconducting, normal metallic or normal pseudoinsulating phases. Furthermore the system supports interesting collective excitation of the charge carriers, which appears in the normal phase, persists in the superconducting phase, but eventually gets destroyed by the superconducting condensate. We also show the possibility of building a phase diagram of a system with the superconducting phase occupying a dome-shaped region on the temperature-disorder plane.Comment: Minor revisions, interpretation clarified, version published in JHE

How small hydrodynamics can go

Numerous experimental and theoretical results in liquids and plasmas suggest the presence of a critical momentum at which the shear diffusion mode collides with a non-hydrodynamic relaxation mode, giving rise to propagating shear waves. This phenomenon, labelled as "k-gap", could explain the surprising identification of a low-frequency elastic behaviour in confined liquids. More recently, a formal study of the perturbative hydrodynamic expansion showed that critical points in complex space, such as the aforementioned k-gap, determine the radius of convergence of linear hydrodynamics, its regime of applicability. In this work, we combine the two new concepts and we study the radius of convergence of linear hydrodynamics in "real liquids" by using several data from simulations and experiments. We generically show that the radius of convergence increases with temperature and it surprisingly decreases with the electromagnetic interactions coupling. More importantly, for all the systems considered, we find that such radius is set by the Wigner-Seitz radius, the characteristic inter-atomic distance of the liquid, which provides a natural microscopic bound.Comment: v2: matching the published versio