Charge-density response in layered metals: Retardation effects, generalized plasma waves, and their spectroscopic signatures

Gabriele, F.; Senese, R.; Castellani, C.; Benfatto, L.

doi:10.1103/physrevb.109.045137

Cited by 2 publications

(3 citation statements)

References 52 publications

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“…To interpret the results in the case of a layered superconductor, and to make a connection with the generalized plasma modes discussed in Refs. [ 18 , 19 , 20 ], we address the same problem within a full-quantum path-integral formalism. In superconductors, plasma modes can be studied via the fluctuations

of the phase of the SC order parameter.…”

Section: Methodsmentioning

confidence: 99%

“…By using realistic values of plasma frequencies in cuprates, one sees that k ∼ µm −1 . As such, this scale is two orders of magnitude smaller than the momenta usually accessible in RIXS [25][26][27][28][29] or EELS [30][31][32] experiments, which are not sensitive to the relativistic regime and probe the plasmon dispersion given by Equation (20).…”

Section: Effective Action Description Of Plasma Modesmentioning

confidence: 99%

“…As extensively discussed in Refs. [ 18 , 19 , 20 ], this mechanism leads to a mixing of the longitudinal and transverse responses inside the material, making the distinction between plasmons and polaritons blurred at momenta smaller than a scale

set by the anisotropy between in-plane

and out-of-plane

plasma frequencies. Since usually

, the effect is relevant for non-linear Josephson plasmonics in the THz regime [ 21 , 22 , 23 , 24 ], but does not affect, e.g., the measurements of plasmons in RIXS [ 25 , 26 , 27 , 28 , 29 ] or EELS [ 30 , 31 , 32 ], which usually measure momenta in a fraction of the Brillouin zone.…”

Section: Introductionmentioning

confidence: 99%

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Optical Absorption in Tilted Geometries as an Indirect Measurement of Longitudinal Plasma Waves in Layered Cuprates

Sellati,

Fiore,

Castellani

et al. 2024

Nanomaterials

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Electromagnetic waves propagating in a layered superconductor with arbitrary momentum, with respect to the main crystallographic directions, exhibit an unavoidable mixing between longitudinal and transverse degrees of freedom. Here we show that this basic physical mechanism explains the emergence of a well-defined absorption peak in the in-plane optical conductivity when light propagates at small tilting angles relative to the stacking direction in layered cuprates. More specifically, we show that this peak, often interpreted as a spurious leakage of the c-axis Josephson plasmon, is instead a signature of the true longitudinal plasma mode occurring at larger momenta. By combining a classical approach based on Maxwell’s equations with a full quantum derivation of the plasma modes based on modeling the superconducting phase degrees of freedom, we provide an analytical expression for the absorption peak as a function of the tilting angle and light polarization. We suggest that an all-optical measurement in tilted geometry can be used as an alternative way to access plasma-wave dispersion, usually measured by means of large-momenta scattering techniques like resonant inelastic X-ray scattering (RIXS) or electron energy loss spectroscopy (EELS).

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of the phase of the SC order parameter.…”

Section: Methodsmentioning

confidence: 99%