Dual character of the electronic structure in YBa2Cu4O8: conduction bands of CuO2 planes and CuO chains

TL;DR

This study uses muARPES to separately analyze the electronic structures of CuO2 planes and CuO chains in YBa2Cu4O8, revealing distinct 2D and 1D behaviors and their hybridization, which advances understanding of high-temperature superconductivity.

Contribution

It provides the first detailed muARPES investigation of both CuO2 planes and CuO chains in YBa2Cu4O8, highlighting their electronic properties and hybridization.

Findings

CuO2 planes exhibit nearly momentum-independent bilayer splitting of 150 meV.

CuO chains show two 1D bands with a 550 meV separation and a 240 meV energy gap.

Electrons are confined within planes and chains with non-trivial hybridization.

Abstract

We use microprobe Angle-Resolved Photoemission Spectroscopy (muARPES) to separately investigate the electronic properties of CuO2 planes and CuO chains in the high temperature superconductor, YBa2Cu4O8. In the CuO2 planes, a two dimensional (2D) electronic structure with nearly momentum independent bilayer splitting is observed. The splitting energy is 150 meV at (pi,0), almost 50% larger than in Bi2Sr2CaCu2O(8+d) and the electron scattering at the Fermi level in the bonding band is about 1.5 times stronger than in the antibonding band. The CuO chains have a quasi one dimensional (1D) electronic structure. We observe two 1D bands separated by ~ 550meV: a conducting band and an insulating band with an energy gap of ~ 240meV. We find that the conduction electrons are well confined within the planes and chains with a non-trivial hybridization.