Quasiparticle dynamics in overdoped Bi$_{1.4}$Pb$_{0.7}$Sr$_{1.9}$CaCu$_{2}$O$_{8+\delta}$: Coexistence of superconducting gap and pseudogap below $T_{c}$

TL;DR

This study investigates quasiparticle relaxation in overdoped Bi2212, revealing coexistence of superconducting gap and pseudogap below Tc, with evidence of increased electron-spin fluctuation scattering in the pseudogap phase.

Contribution

It provides experimental evidence of pseudogap presence and coexistence with the superconducting gap in overdoped Bi2212, highlighting changes in scattering dynamics.

Findings

Identification of a 22 meV pseudogap at doping p=0.22

Coexistence of superconducting gap and pseudogap below Tc

Increased electron-spin fluctuation scattering in the pseudogap phase

Abstract

Photoexcited quasiparticle relaxation dynamics in overdoped Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ ($T_{c}$=65~K, hole doping $p$=0.22) single crystal is investigated as a function of temperature. We provide evidence of a $\sim$22~meV pseudogap ($T^{\ast}$$\approx$100~K) at this doping level. Our data support the scenario where both the superconducting gap and pseudogap coexist in the superconducting state. Our results also suggest an increased scattering rate between electrons and spin fluctuations as the sample enters the pseudogap phase.