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1. chinaXiv:201612.00088 [pdf]

A holographic study on vector condensate induced by a magnetic field

Cai, Rong-Gen; He, Song; Li, Li; Li, Li-Fang
Subjects: Geosciences >> Space Physics

We study a holographic model with vector condensate by coupling the anti-de Sitter gravity to an Abelian gauge field and a charged vector field in (3 + 1) dimensional spacetime. In this model there exists a non-minimal coupling of the vector field to the gauge field. We find that there is a critical temperature below which the charged vector condenses via a second order phase transition. The DC conductivity becomes infinite and the AC conductivity develops a gap in the condensed phase. We study the effect of a background magnetic field on the system. It is found that the background magnetic field can induce the condensate of the vector field even in the case without chemical potential/charge density. In the case with non-vanishing charge density, the transition temperature raises with the applied magnetic field, and the condensate of the charged vector operator forms a vortex lattice structure in the spatial directions perpendicular to the magnetic field.

submitted time 2016-12-22 Hits1564Downloads794 Comment 0

2. chinaXiv:201612.00087 [pdf]

Vector condensate and AdS soliton instability induced by a magnetic field

Cai, Rong-Gen; Li, Li; Li, Li-Fang; Wu, You
Subjects: Geosciences >> Space Physics

We continue to study the holographic p-wave superconductor model in the Einstein-Maxwell-complex vector field theory with a non-minimal coupling between the complex vector field and the Maxwell field. In this paper we work in the AdS soliton background which describes a conformal field theory in the confined phase and focus on the probe approximation. We find that an applied magnetic field can lead to the condensate of the vector field and the AdS soliton instability. As a result, a vortex lattice structure forms in the spatial directions perpendicular to the applied magnetic field. As a comparison, we also discuss the vector condensate in the Einstein-SU(2) Yang-Mills theory and find that in the setup of the present paper, the Einstein-Maxwell-complex vector field model is a generalization of the SU(2) model in the sense that the vector field has a general mass and gyromagnetic ratio.

submitted time 2016-12-22 Hits1355Downloads767 Comment 0

3. chinaXiv:201612.00085 [pdf]

Competition between s-wave order and d-wave order in holographic superconductors

Li, Li-Fang; Cai, Rong-Gen; Li, Li; Wang, Yong-Qiang
Subjects: Geosciences >> Space Physics

We study competition between s-wave order and d-wave order through two holographic superconductor models. We find that once the coexisting phase appears, it is always thermodynamically favored, and that the coexistence phase is narrow and one condensate tends to kill the other. The phase diagram is constructed for each model in terms of temperature and the ratio of charges of two orders. We further compare the behaviors of some thermodynamic quantities, and discuss the different aspects and identical ones between two models.

submitted time 2016-12-22 Hits1383Downloads768 Comment 0

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