Shadow Bands in the Cuprates

TL;DR

This paper investigates shadow bands in high-Tc cuprates, showing they are more prominent in underdoped compounds and could be observed in photoemission experiments, aligning with recent experimental data.

Contribution

It provides a theoretical analysis of shadow bands in the Hubbard and t-J models using Monte Carlo and exact diagonalization, clarifying their doping dependence.

Findings

Shadow bands are more visible in underdoped cuprates.

Overdoped cuprates likely hide shadow bands in background noise.

Results align with recent experimental observations.

Abstract

A consequence of strong antiferromagnetic correlations in models of high-Tc cuprates is the appearance in photoemission (PES) calculations of considerable more weight above the Fermi momentum ${\rm {\bf p}_F }$ than expected for non-interacting electrons. This effect, first discussed by Kampf and Schrieffer (Phys. Rev. {\bf B 41}, 6399 (1990)) under the name of ``shadow bands'', is here analyzed in the two dimensional Hubbard and t-J models using Monte Carlo and exact diagonalization techniques. It is concluded that for underdoped compounds weight above ${\rm {\bf p}_F }$ could be observable in experimental PES data, while in the overdoped regime it will be likely hidden in the experimental background. In the intermediate region the signal is weak. Our results are thus compatible with recent experimental data by Aebi et al. (Phys. Rev. Lett. {\bf 72}, 2757 (1994)) for Bi2212 at optimal doping. However, to definitely prove the existence of this effect in the cuprates, experiments in the underdoped regime are necessary.