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Journal Articles Physical Review B: Condensed Matter and Materials Physics (1998-2015) Year : 2016

## $\eta$ collective mode as A$_{1g}$ Raman resonance in cuprate superconductors

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X. Montiel
• Function : Author
T. Kloss
• Function : Author
C. Pépin
• Function : Author
S. Benhabib
• Function : Author
Y. Gallais
A. Sacuto

#### Abstract

We discuss the possible existence a spin singlet excitation with charge ±2 (η-mode) originating the A 1g Raman resonance in cuprate superconductors. This η-mode relates the d-wave superconducting singlet pairing channel to a d-wave charge channel. We show that the η boson forms a particle-particle bound state below the 2∆ threshold of the particle-hole continuum where ∆ is the maximum d-wave gap. Within a generalized random phase approximation and Bethe-Salpether approximation study, we find that this mode has energies similar to the resonance observed by Inelastic Neutron Scattering (INS) below the superconducting (SC) coherent peak at 2∆ in various SC cuprates compounds. We show that it is a very good candidate for the resonance observed in Raman scattering below the 2∆ peak in the A 1g symmetry. Since the η-mode sits in the S = 0 channel, it may be observable via Raman, X-ray or Electron Energy Loss Spectroscopy probes.

### Dates and versions

cea-01469552 , version 1 (16-02-2017)

### Identifiers

• HAL Id : cea-01469552 , version 1
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### Cite

X. Montiel, T. Kloss, C. Pépin, S. Benhabib, Y. Gallais, et al.. $\eta$ collective mode as A$_{1g}$ Raman resonance in cuprate superconductors. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2016, 93 (2), ⟨10.1103/PhysRevB.93.024515⟩. ⟨cea-01469552⟩

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