Doping-dependence of nodal quasiparticle properties in high-$T_{\rm c}$ cuprates studied by laser-excited angle-resolved photoemission spectroscopy

TL;DR

This study uses laser ARPES to analyze how doping affects low-temperature nodal quasiparticle properties in high-$T_c$ cuprates, revealing doping-dependent scattering rates and the influence of electronic inhomogeneity.

Contribution

It provides high-resolution measurements of quasiparticle dispersions, scattering rates, and their doping dependence in Bi2212, highlighting the role of electronic inhomogeneity.

Findings

Quasiparticle peaks are sharp in optimally and overdoped samples.

Energy dependence of scattering rate follows |ω| across doping levels.

Underdoped samples show increased scattering rates at zero energy.

Abstract

We investigate the doping dependent low energy, low temperature ($T$ = 5 K) properties of nodal quasiparticles in the d-wave superconductor Bi$_{2.1}$Sr$_{1.9}$CaCu$_2$O$_{8+\delta}$ (Bi2212). By utilizing ultrahigh resolution laser-excited angle-resolved photoemission spectroscopy, we obtain precise band dispersions near $E_{F}$, mean free paths and scattering rates ($\Gamma$) of quasiparticles. For optimally and overdoped, we obtain very sharp quasiparticle peaks of 8 meV and 6 meV full-width at half-maximum, respectively, in accord with terahertz conductivity. For all doping levels, we find the energy-dependence of $\Gamma \sim |\omega |$, while $\Gamma$($\omega =0$) shows a monotonic increase from overdoping to underdoping. The doping dependence suggests the role of electronic inhomogeneity on the nodal quasiparticle scattering at low temperature (5 K $\lsim 0.07T_{\rm c}$), pronounced in the underdoped region.