"Kinks", Nodal Bilayer Splitting and Interband Scattering in YBCO

TL;DR

This study uses advanced ARPES techniques to analyze YBCO, revealing universal features of nodal quasiparticles, including kinks, bilayer splitting, and interband scattering, linked to spin fluctuations across cuprate superconductors.

Contribution

It provides new evidence of universal electron dynamics and spin-fluctuation effects in bilayer cuprates, expanding understanding beyond BSCCO.

Findings

Detection of nodal kinks and bilayer splitting in YBCO

Evidence of strong interband scattering

Correlation of kinks with spin-1 resonance energy

Abstract

We apply the new-generation ARPES methodology to the most widely studied cuprate superconductor YBCO. Considering the nodal direction, we found noticeable renormalization effects known as "kinks" both in the quasiparticle dispersion and scattering rate, the bilayer splitting and evidence for strong interband scattering -- all the characteristic features of the nodal quasiparticles detected earlier in BSCCO. The typical energy scale and the doping dependence of the "kinks" clearly point to their intimate relation with the spin-1 resonance seen in the neutron scattering experiments. Our findings strongly suggest a universality of the electron dynamics in the bilayer superconducting cuprates and a dominating role of the spin-fluctuations in the formation of the quasiparticles along the nodal direction.