Coherent quasi-particles-to-incoherent hole-carriers crossover in underdoped cuprates

TL;DR

This paper investigates the transition from coherent quasi-particles to incoherent hole carriers in underdoped cuprates, revealing how coherence temperature varies with doping and its relation to superconductivity and pseudogap phenomena.

Contribution

It introduces the concept of coherence temperature for quasi-particles on Fermi arcs and shows its doping dependence, linking coherence to superconductivity emergence.

Findings

Coherence temperature $T_{coh}$ increases with doping.

Superconductivity occurs below both $T^*$ and $T_{coh}$.

Incoherent carriers dominate transport in underdoped cuprates.

Abstract

In underdoped cuprates, only a portion of the Fermi surface survives as Fermi arcs due to pseudogap opening. In hole-doped La$_{2}$CuO$_4$, we have deduced the "coherence temperature" $T_{coh}$ of quasi-particles on the Fermi arc above which the broadened leading edge position in angle-integrated photoemission spectra is shifted away from the Fermi level and the quasi-particle concept starts to lose its meaning. $T_{coh}$ is found to rapidly increase with hole doping, an opposite behavior to the pseudogap temperature $T^*$. The superconducting dome is thus located below both $T^*$ and $T_{coh}$, indicating that the superconductivity emerges out of the coherent Fermionic quasi-particles on the Fermi arc. $T_{coh}$ remains small in the underdoped region, indicating that incoherent charge carriers originating from the Fermi arc are responsible for the apparently metallic transport at high temperatures.