High-energy kink in the dispersion of a hole in an antiferromagnet: Double-occupancy effects on electronic excitations

Abstract

Evolution of the hole spectral function along the $\ensuremath{\Gamma}\text{\ensuremath{-}}(\ensuremath{\pi},\ensuremath{\pi})$ cut is studied in the antiferromagnetic state of the Hubbard model. The kink in the calculated hole dispersion, the sharp spectral-weight transfer between the branches, and the drastically suppressed coherent spectral weight near $\mathbf{k}=(0,0)$, as observed recently in the high-resolution angle resolved photoemission spectroscopy studies of cuprate antiferromagnets, are shown to be strongly enhanced by finite-$U$ double-occupancy effects. Together with the anomalous spin-wave dispersion observed earlier in high-resolution neutron-scattering studies, the present study provides further evidence of a unified description of magnetic and electronic excitations in cuprate antiferromagnets in terms of the Hubbard model.