Nature and Raman signatures of the Higgs amplitude mode in the coexisting superconducting and charge-density-wave state

Abstract

We investigate the behavior of the Higgs (amplitude) mode when superconductivity emerges on a preexisting charge-density-wave state. We show that the weak overdamped square-root singularity of the amplitude fluctuations in a standard BCS superconductor is converted in a sharp, undamped power-law divergence in the coexisting state, reminiscent of the Higgs behavior in Lorentz-invariant theories. This effect reflects in a strong superconducting resonance in the Raman spectra, both for an electronic and a phononic mechanism leading to the Raman visibility of the Higgs. In the latter case, our results are relevant to the interpretation of the Raman spectra measured experimentally in NbSe2.

Extended version, accepted for publication in PRB

References in corpus (7)

• Inelastic Light Scattering From Correlated Electrons
• The `Higgs' Amplitude Mode at the Two-Dimensional Superfluid-Mott Insulator Transition
• Two energy gaps and Fermi surface 'arcs' in NbSe2
• Quasi-Particle Spectra, Charge-Density-Wave, Superconductivity and Electron-Phonon Coupling in 2H-NbSe2
• Detecting the Amplitude Mode of Strongly Interacting Lattice Bosons by Bragg Scattering
• The Higgs mode in a two-dimensional superfluid
• Charged-phonon theory and Fano effect in the optical spectroscopy of bilayer graphene

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• Mechanism of High-Temperature Superconductivity in Correlated-Electron Systems
• Charge and pairing dynamics in the attractive Hubbard model: mode coupling and the validity of linear-response theory