Intermediate scalings in holographic RG flows and conductivities

We construct the simplest gravitational dual model of a superconductor on Qlattices. We analyze the condition for the existence of a critical temperature at which the charged scalar field will condense. In contrast to the holographic superconductor on ionic lattices, the presence of Q-lattices will suppress the condensate of the scalar field and lower the critical temperature. In particular, when the Q-lattice background is dual to a deep insulating phase, the condensation would never occur for some small charges. Furthermore, we numerically compute the optical conductivity in the superconducting regime. It turns out that the presence of Q-lattice does not remove the pole in the imaginary part of the conductivity, ensuring the appearance of a delta function in the real part. We also evaluate the gap which in general depends on the charge of the scalar field as well as the Q-lattice parameters. Nevertheless, when the charge of the scalar field is relatively large and approaches the probe limit, the gap becomes universal with ω g 9T c which is consistent with the result for conventional holographic superconductors.

Section: T/tcmentioning

confidence: 99%

Holographic superconductor on Q-lattice

Ling

Liu

Niu

et al. 2015

“…Furthermore, for sufficiently large deformations, the boomerang RG flow has an intermediate scaling regime that is dominated by the Lifshitz-like fixed point of [4] that appears in the parabolic class. Such flows can therefore be viewed as an interesting framework for resolving the singularity of the Lifshitz-like fixed point, differing from other singularity resolving flows [11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Boomerang RG flows in M-theory with intermediate scaling

Donos

Gauntlett

Rosen

et al. 2017

We construct novel RG flows of D=11 supergravity that asymptotically approach AdS 4 × S 7 in the UV with deformations that break spatial translations in the dual field theory. In the IR the solutions return to exactly the same AdS 4 × S 7 vacuum, with a renormalisation of relative length scales, and hence we refer to the flows as 'boomerang RG flows'. For sufficiently large deformations, on the way to the IR the solutions also approach two distinct intermediate scaling regimes, each with hyperscaling violation. The first regime is Lorentz invariant with dynamical exponent z = 1 while the second has z = 5/2. Neither of the two intermediate scaling regimes are associated with exact hyperscaling violation solutions of D = 11 supergravity. The RG flow solutions are constructed using the four dimensional N = 2 STU gauged supergravity theory with vanishing gauge fields, but non-vanishing scalar and pseudoscalar fields. In the ABJM dual field theory the flows are driven by spatially modulated deformation parameters for scalar and fermion bilinear operators.

“…These have instabilities due to the occurrence of linearised scalar fluctuations that violate the BF bound, but in one of the cases one could consider a consistently-truncated sub-theory within which the new AdS 4 vacuum would be stable. In particular, it would be interesting to construct domain-wall geometries which interpolate between two AdS 4 fixed points, and ask whether any intermediate scaling behavior is possible along the flow, as in the construction of [24]. Finally, while some of the features we have observed in this paper have analogs in the behavior of strongly correlated materials in the presence of a magnetic field, we would like to refine these ideas further and make these connections more concrete.…”

Section: Jhep04(2015)074mentioning

confidence: 91%

“…It would be interesting to construct domain-wall geometries which interpolate between two AdS 4 fixed points, along the lines of [22,23]. Moreover, given the structure of the scalar potential and gauge couplings in our truncation -and in particular, the fact that they generically give rise to hyperscaling violating solutions -we wonder whether there may be some overlap with the construction of [24], where the intermediate geometry was associated…”

Section: Jhep04(2015)074mentioning

confidence: 99%

Superfluid and metamagnetic phase transitions in ω-deformed gauged supergravity

Cremonini

Pang

Pope

et al. 2015

We study non-supersymmetric truncations of ω-deformed N = 8 gauged supergravity that retain a U(1) gauge field and three scalars, of which two are neutral and one charged. We construct dyonic domain-wall and black hole solutions with AdS 4 boundary conditions when only one (neutral) scalar is non-vanishing, and examine their behavior as the magnetic field and temperature of the system are varied. In the infrared the domainwall solutions approach either dyonic AdS 2 × R 2 or else Lifshitz-like, hyperscaling violating geometries. The scaling exponents of the latter are z = 3/2 and θ = −2, and are independent of the ω-deformation. New ω-dependent AdS 4 vacua are also identified. We find a rich structure for the magnetization of the system, including a line of metamagnetic first-order phase transitions when the magnetic field lies in a particular range. Such transitions arise generically in the ω-deformed theories. Finally, we study the onset of a superfluid phase by allowing a fluctuation of the charged scalar field to condense, spontaneously breaking the abelian gauge symmetry. The mechanism by which the superconducting instability ceases to exist for strong magnetic fields is different depending on whether the field is positive or negative. Finally, such instabilities are expected to compete with spatially modulated phases.