Charge carrier correlation in the electron-doped t-J model

TL;DR

This study uses exact diagonalization to analyze the electron-doped t-J model, revealing persistent antiferromagnetic correlations and small Fermi pockets up to 12.5% doping, with no Fermi surface shape change observed.

Contribution

The paper provides detailed numerical analysis of the electron-doped t-J model, showing the stability of antiferromagnetic order and Fermi surface features at low doping levels.

Findings

Robust antiferromagnetic correlations up to 12.5% doping

Fermi surface consists of small pockets at single-carrier momenta

No change in Fermi surface shape observed up to maximum doping studied

Abstract

We study the t-t'-t''-J model with parameters chosen to model an electron-doped high temperature superconductor. The model with one, two and four charge carriers is solved on a 32-site lattice using exact diagonalization. Our results demonstrate that at doping levels up to x=0.125 the model possesses robust antiferromagnetic correlation. When doped with one charge carrier, the ground state has momenta (\pm\pi,0) and (0,\pm\pi). On further doping, charge carriers are unbound and the momentum distribution function can be constructed from that of the single-carrier ground state. The Fermi surface resembles that of small pockets at single charge carrier ground state momenta, which is the expected result in a lightly doped antiferromagnet. This feature persists upon doping up to the largest doping level we achieved. We therefore do not observe the Fermi surface changing shape at doping levels up to 0.125.