The Dichotomy between Nodal and Antinodal Quasiparticles in Underdoped (La$_{2-x}$Sr$_x$)CuO$_4$ Superconductors

TL;DR

This study uses high-resolution ARPES to reveal a sharp contrast between well-defined nodal quasiparticles and suppressed antinodal quasiparticles in underdoped LSCO, indicating an additional scattering mechanism at play.

Contribution

It identifies a specific low-energy scattering process affecting antinodal quasiparticles, advancing understanding of quasiparticle behavior in underdoped cuprates.

Findings

Nodal quasiparticles are well-defined below 70 meV.

Antinodal quasiparticles disappear abruptly away from the nodal point.

Scattering across parallel Fermi surface segments likely causes the suppression.

Abstract

High resolution angle-resolved photoemission measurements on underdoped (La$_{2-x}$Sr$_x$)CuO$_4$ system show that, at energies below 70 meV, the quasiparticle peak is well defined around the ($\pi$/2,$\pi$/2) nodal region and disappears rather abruptly when the momentum is changed from the nodal point to the ($\pi$,0) antinodal point along the underlying ``Fermi surface''. It indicates that there is an extra low energy scattering mechanism acting upon the antinodal quasiparticles. We propose that this mechanism is the scattering of quasiparticles across the nearly parallel segments of the Fermi surface near the antinodes.