ARPES Spectral Function in Lightly Doped and Antiferromagnetically Ordered YBa2Cu3O{6+y}

TL;DR

This paper calculates the electron spectral function in lightly doped YBa2Cu3O6+y using the extended t-J model, revealing small hole pockets, anisotropic spectral intensity, and suppressed bilayer splitting in the antiferromagnetic regime.

Contribution

It provides a controlled theoretical calculation of the spectral function in lightly doped YBa2Cu3O6+y, highlighting the effects of antiferromagnetism on the Fermi surface and bilayer splitting.

Findings

Fermi surface consists of small hole pockets at (,)

Spectral function is highly anisotropic with maximum intensity inside pockets

Antiferromagnetic correlations suppress bilayer splitting

Abstract

At doping below 6% the bilayer cuprate YBa2Cu3O{6+y} is a collinear antiferromagnet. Independent of doping the value of the staggered magnetization at zero temperature is about 0.6\mu_B. This is the maximum value of the magnetization allowed by quantum fluctuations of localized spins. In this low doping regime the compound is a normal conductor with a finite resistivity at zero temperature. These experimental observations create a unique opportunity for theory to perform a controlled calculation of the electron spectral function. In the present work we perform this calculation within the framework of the extended t-J model. As one expects the Fermi surface consists of small hole pockets centered at (\pi/2,\pi/2). The electron spectral function is very strongly anisotropic with maximum of intensity located at the inner parts of the pockets and with very small intensity at the outer parts. We also found that the antiferromagnetic correlations act against the bilayer bonding-antibonding splitting destroying it. The bilayer Fermi surface splitting is practically zero.