Evolution of Coherence and Superconductivity in Electron-Doped Cuprates

TL;DR

This study uses electronic Raman spectroscopy to analyze how coherence and superconductivity evolve in electron-doped cuprates, revealing the role of coherent quasiparticles and their doping-dependent behavior.

Contribution

It provides new insights into the doping dependence of quasiparticle coherence and the superconducting order parameter in electron-doped cuprates.

Findings

Superconducting gap magnitude varies between 4.6 and 3.5 k_B T_c.

Doped carriers split into coherent quasiparticles and incoherent carriers.

Only coherent quasiparticles contribute to superfluid density.

Abstract

The electron-doped cuprates were studied by electronic Raman spectroscopy across the entire region of the superconducting (SC) phase diagram. We determined that the magnitude of the SC order parameter varies between 4.6 and 3.5 k_BT_c, consistent with weak coupling BCS theory. Using a ``Raman conductivity" sum rule, we found that doped carriers divide into coherent quasi-particles (QPs) and carriers that remain incoherent. The coherent QPs mainly reside in the vicinity of (pi/2a, pi/2a) regions of the Brillouin zone. The carriers doped beyond optimal doping remain incoherent. Only coherent QPs contribute to the superfluid density in the SC state.