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 $T_{c}$

摘要

Photoexcited quasiparticle relaxation dynamics in overdopedBi$_{2}$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 provideevidence of a $\sim$22~meV pseudogap ($T^{\ast}$$\approx$100~K) at this dopinglevel. Our data support the scenario where both the superconducting gap andpseudogap coexist in the superconducting state. Our results also suggest anincreased scattering rate between electrons and spin fluctuations as the sampleenters the pseudogap phase.