Optical Properties of Bogoliubov Quasiparticles

Abstract

We calculated the optical conductivity $\sigma (T,\Omega )$ of a gas of Bogoliubov quasiparticles (BQP) from their Green's function and the Kubo formula. We compare with corresponding normal state (N) and superconducting state (SC) results. The superconducting case includes the dynamic response of the condensate through additional contributions to the Kubo formula involving the Gor'kov anomalous Green's function. The differences in the optical scattering rate are largest just above the optical gap and become progressively smaller as the photon energy is increased or the temperature is raised. Our results are compared with those obtained using a recently advocated phenomenological procedure for eliminating the effect of the condensate [1]. The $\delta$-function contribution at zero photon energy, proportional to the superfluid density, is dropped in the real part of the conductivity $[{\sigma }_1(T,\Omega )]$ and its Kramers-Kronig transform is subtracted from the imaginary part ${\sigma }_2(T,\Omega )$. This results in deviations from our BQP and superconducting state optical scattering rates even in the region where these have merged and are, in addition, close to the normal state result.

11 pages, 10 figures Accepted for publication in Physical Review B

References in corpus (7)

• High-temperature superconductivity in iron-based materials
• Scanning tunneling spectroscopy of high-temperature superconductors
• Lattice symmetry breaking in cuprate superconductors: Stripes, nematics, and superconductivity
• Cubic H${}_3$S around 200 GPa: an atomic hydrogen superconductor stabilized by sulfur
• On the Relation between Optical Conductivity and Quasiparticle Dynamics: Boson Structures
• Spin Dynamics in Cuprates: Optical Conductivity of HgBa2CuO4
• The fate of quasiparticles in the superconducting state

Cited by in corpus (1)

• Excitonic instability in optically-pumped three-dimensional Dirac materials