Inhomogeneous structures in holographic superfluids. II. Vortices

We investigate holographic models of superfluids and superconductors in which the gravitational theory includes a dilatonic field. Dilaton extensions are interesting as they allow us to obtain a better description of low temperature condensed matter systems. We focus on asymptotically AdS black hole configurations, which are dual to field theories with conformal ultraviolet behavior. A nonvanishing value of the dilaton breaks scale invariance in the infrared and is therefore compatible with the normal phase being insulating (or a solid in the fluid mechanical interpretation); indeed we find that this is the case at low temperatures and if one appropriately chooses the parameters of the model. Not only the superfluid phase transitions, but also the response to external gauge fields is analyzed. This allows us to study, among other things, the vortex phase and to show that these holographic superconductors are also of Type II. However, at low temperatures they can behave in a qualitatively different way compared to their analogues without the dilaton: the critical magnetic fields and the penetration depth can remain finite in the small T /T c limit.

Section: Introduction and Resultssupporting

confidence: 69%

Holographic superfluids and superconductors in dilaton-gravity

Salvio

2012

“…1 The system we consider is a (2 + 1)-dimensional relativistic superfluid. Studies of various aspects of that particular holographic superfluid include [21][22][23]. A study of its time-evolution as it relaxes from a far-from-equilibrium initial state, corresponding to an ensemble of vortex defects, was performed in [24].…”

Section: Jhep05(2015)070mentioning

confidence: 99%

Non-thermal fixed point in a holographic superfluid

Ewerz

Gasenzer

Karl

et al. 2015

Abstract:We study the far-from-equilibrium dynamics of a (2 + 1)-dimensional superfluid at finite temperature and chemical potential using its holographic description in terms of a gravitational system in 3 + 1 dimensions. Starting from various initial conditions corresponding to ensembles of vortex defects we numerically evolve the system to long times. At intermediate times the system exhibits Kolmogorov scaling the emergence of which depends on the choice of initial conditions. We further observe a universal latetime regime in which the occupation spectrum and different length scales of the superfluid exhibit scaling behaviour. We study these scaling laws in view of superfluid turbulence and interpret the universal late-time regime as a non-thermal fixed point of the dynamical evolution. In the holographic superfluid the non-thermal fixed point can be understood as a stationary point of the classical equations of motion of the dual gravitational description.

“…In this paper we will study a consequence of this cohabitation by probing the IR structure with an excitation that all such phases possess: a vortex. Previous studies of holographic superfluid and superconducting vortices include [6][7][8][9][10][11][12]. The basic idea is well-understood: the vortex becomes a cosmic string in the bulk, carrying magnetic flux down to the bulk horizon.…”

Section: Jhep04(2014)096mentioning

confidence: 99%

“…entropy, energy and Helmoltz free energy of isolated gravitational vortices at nonzero temperature. 8 We will see that some of their global thermodynamic properties strongly depend on q. We start with the entropy.…”

Section: Field-theoretic and Thermodynamic Observablesmentioning

confidence: 99%

Vortices in holographic superfluids and superconductors as conformal defects

Dias

Horowitz

Iqbal³

et al. 2014

We present a detailed study of a single vortex in a holographic symmetry breaking phase. At low energies the system flows to an nontrivial conformal fixed point. Novel vortex physics arises from the interaction of these gapless degrees of freedom with the vortex: at low energies the vortex may be understood as a conformal defect in this low energy theory. Defect conformal symmetry allows the construction of a simple infrared geometry describing a new kind of extremal horizon: a Poincaré horizon with a small bubble of magnetic Reissner-Nordström horizon inside it that carries a single unit of magnetic flux and a finite amount of entropy even at zero temperature. We also construct the full geometry describing the vortex at finite temperature in a UV complete theory. We study both superfluid and superconducting boundary conditions and calculate thermodynamic properties of the vortex. A study of vortex stability reveals that the dual superconductor can be Type I or Type II, depending on the charge of the condensed scalar. Finally, we study forces on a moving vortex at finite temperature from the point of view of defect conformal symmetry and show that these forces can be expressed in terms of Kubo formulas of defect CFT operators.