Elastic forward scattering in the cuprate superconducting state

Abstract

We investigate the effect of elastic forward scattering on the ARPES spectrum of the cuprate superconductors. In the normal state, small angle scattering from out-of-plane impurities is thought to broaden the ARPES spectral response with minimal effect on the resistivity or the superconducting transition temperature Tc. Here we explore how such forward scattering affects the ARPES spectrum in the d-wave superconducting state. Away from the nodal direction, the one-electron impurity scattering rate is found to be suppressed as ω approaches the gap edge by a cancellation between normal and anomalous scattering processes, leading to a square-root-like feature in the spectral weight as ω approaches −∆ k from below. For momenta away from the Fermi surface, our analysis suggests that a dirty optimally or overdoped system will still display a sharp but nondispersive peak which could be confused with a quasiparticle spectral feature. Only in cleaner samples should the true dispersing quasiparticle peak become visible. At the nodal point on the Fermi surface, the contribution of the anomalous scattering vanishes and the spectral weight exhibits a Lorentzian quasiparticle peak in both energy and momentum. Our analysis, including a treatment of unitary scatterers and inelastic spin fluctuation scattering, suggests explanations for the sometimes mysterious lineshapes and temperature dependences of the peak structures observed in the Bi2Sr2CaCu2O8 system.

Angle and frequency dependence of self-energy from spin fluctuation mediated d-wave pairing for high temperature superconductors

“…The shape of Σ(k, ω) are also modified by the impurity scatterings. [18] The VHS peak may be substantially suppressed by the coupling to boson spectrum and impurity scatterings. One should perform the selfconsistent calculations to see their effects without misleading conclusion.…”

Anisotropic scattering rate in Fe-substitutedBi2Sr2Ca(Cu1−xFex)2Naamneh1, Lubashevsky2, Lahoud3 et al. 2015Phys. Rev. B1000View full textAdd to dashboardCite

“…Impurities away from the CuO planes induce a relatively smooth potential, so the effective scattering range should be long. As a result, the out-of-plane impurities will induce mainly forward scattering which will strongly reduce the life-time of the anti-nodal quasi-particles without increasing the residual resistivity [19]. Optical conductivity measurements using the same kind of samples found that the Fe substitution reduces the superfluid density of the samples [20], this is expected to reduce T c since according to the Uemura relation T c ∝ n s .…”

Modification of Born impurity scattering near the surface ofd-wave superconductors and influence of external magnetic field

“…In the high-T c cuprate compounds it is believed that scatterers within the CuO 2 planes act as unitary scatterers and thus should have little influence on the Andreev bound states. However, it has been recognized recently that scatterers sitting between the CuO 2 planes are poorly screened and act as Born scatterers 17,18,19 . These impurities are thus expected to have a dominating influence on the broadening of the Andreev bound states.…”