Generalized Josephson plasmons in bilayer superconductors

Abstract

Layered superconductors like High-Tc cuprates display out-of-plane plasma oscillations between layers sustained by the weak Josephson coupling among the superconducting sheets, the so-called Josephson plasmons. Bilayer cuprates hosts two of such modes, but due to the anisotropy of the electronic response their description at generic wavevector cannot be separated from that of the in-plane oscillations. In this paper we provide an analytical theoretical framework able to describe the dispersions and the polarizations of the generalized plasma modes of such systems, that has been only partly addressed by previous work in the literature. We then employ it to explain the peculiar characteristics of their linear optical response, by providing a fully microscopic explanation for the appearance of a finite-frequency peak in the real part of the optical conductivity. On a wider perspective, the complete characterization of the Josephson plasma modes provided by our approach represents a groundwork to address open issues raised by recent experiments with strong THz pulses, able to drive them beyond the linear-response regime.

21 pages, 8 figures

References in corpus (2)

• Persistence of superconducting condensate far above the critical temperature in YBa${}_2$(Cu,Zn)${}_3$O${}_y$ revealed by $c$-axis optical conductivity measurements for several Zn concentrations and carrier doping levels
• Transiently enhanced interlayer tunneling in optically driven high $T_c$ superconductors

Cited by in corpus (10)

• Principles of 2D terahertz spectroscopy of collective excitations: the case of Josephson plasmons in layered superconductors
• Investigating Josephson plasmons in layered cuprates via nonlinear terahertz spectroscopy
• Ghost Josephson plasmon in bilayer superconductors
• Bardasis-Schrieffer-like phase mode in a superconducting bilayer
• Linear spectroscopy of collective modes and the gap structure in two-dimensional superconductors
• Direct observation of the Higgs particle in a superconductor by non-equilibrium Raman scattering
• 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
• Enhanced coherent terahertz emission from critical superconducting fluctuations in YBa${}_2$Cu${}_3$O${}_{6.6}$