Using a new variant of photoelectron spectroscopy, we measure the homogeneous near-nodal pairing ($\Delta$) and pair-breaking self-energy ($\Gamma_S$) processes for a wide range of doping levels of Bi$_2$Sr$_2$CaCu$_2$O$_{ 8+\delta}$. For all samples we find that the pairing extends above the superconducting transition T$_c$ to a scale T$_{ Pair}$ that is distinct from the antinodal pseudogap scale T$^*$ and near but slightly above T$_c$. We find that $\Delta$ and T$_{ Pair}$ are related with a strong coupling ratio 2$\Delta$ /k$_B$T$_{ Pair}\approx6$ across the entire doping phase diagram, i.e. independent of the effects of antinodal pseudogaps or charge-density waves.
Categories: cond-mat.supr-con cond-mat.str-el