paper

Enhancement of superconductivity at the onset of charge-density-wave order in a metal

arXiv:1507.03583 · doi:10.1103/PhysRevB.92.125108

Abstract

We analyze superconductivity in the cuprates near the onset of an incommensurate charge density wave (CDW) order with momentum , as observed in the experiments. We first consider a semi-phenomenological charge-fermion model in which hot fermions, separated by , attract each other by exchanging soft CDW fluctuations. We find that in a quantum-critical region near CDW transition, , where is charge-fermion coupling and is the prefactor which we explicitly compute. We then consider the particular microscopic scenario in which CDW order parameter emerges as a composite field made out of primary spin-density-wave fields. We show that charge-fermion coupling is of order of spin-fermion coupling . As the consequence, superconducting is substantially enhanced near the onset of CDW order. Finally we analyze the effect of an external magnetic field . We show that, as increases, optimal decreases and the superconducting dome becomes progressively more confined to the CDW quantum-critical point. These results are consistent with the experiments.

17 pages, 12 figures, to match the published version

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