Generalized plasma waves in layered superconductors

Abstract

In a layered and strongly anisotropic superconductor the hybrid modes provided by the propagation of electromagnetic waves in the matter identify two well separate energy scales connected to the large in-plane plasma frequency and to the soft out-of-plane Josephson plasmon. Despite the wide interest in their detection and manipulation by means of different experimental protocols, a unified description of plasma waves valid at arbitrary energy and momentum is still lacking. Here we provide a complete description of generalized plasma waves in a layered superconductors by taking advantage of their connection to the gauge-invariant superconducting phase. We show that the anisotropy of the superfluid response leads to two intertwined hybrid light-matter modes with mixed longitudinal and transverse character, while a purely longitudinal plasmon is only recovered for wavevectors larger than the crossover scale set in by the plasma-frequencies anisotropy. Interestingly, below such scale both modes appears with equal weight in the physical density response. Our results open a promising perspective for plasmonic applications made possible by the next-generation spectroscopic techniques able to combine sub-micron momentum resolution with THz energy resolution.

19 pages, 7 figures

References in corpus (4)

• Infrared nano-spectroscopy and imaging of collective superfluid excitations in conventional and high-temperature superconductors
• Terahertz phase slips in striped La${}_{2-x}$Ba${}_x$CuO${}_4$
• Comment on: Crossover of Charge Fluctuations across the Strange Metal Phase Diagram
• Reply to arXiv:2103.10268 `Comment on "Crossover of Charge Fluctuations across the Strange Metal Phase Diagram'''

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• Generalized Josephson plasmons in bilayer superconductors
• Plasmon dispersion in bilayer cuprate superconductors
• Investigating Josephson plasmons in layered cuprates via nonlinear terahertz spectroscopy
• Probing the bulk plasmon continuum of layered materials through electron energy loss spectroscopy in a reflection geometry
• Ghost Josephson plasmon in bilayer superconductors
• Linear spectroscopy of collective modes and the gap structure in two-dimensional superconductors
• Structure factors and quantum geometry in multiband BCS superconductors
• Optical absorption in tilted geometries as an indirect measurement of longitudinal plasma waves in layered cuprates
• Charge density response in layered metals: retardation effects, generalized plasma waves and their spectroscopic signatures
• Two-dimensional THz spectroscopy in electronic systems: a many-body diagrammatic approach
• Strongly correlated model of acousticlike plasmons persisting across the phase diagram of cuprate superconductors