Photoemission spectra of ${\rm Sr_2 Cu O_2 Cl_2}$: a theoretical analysis

TL;DR

This paper compares recent ARPES data on Sr2CuO2Cl2 with theoretical models, showing that the observed hole dispersion can be approximated by the t-t'-J and three-band Hubbard models with realistic parameters.

Contribution

It provides a theoretical analysis linking ARPES results to the t-t'-J and three-band Hubbard models, clarifying the role of parameters like t' and t_{pp}.

Findings

Experimental ARPES data shows small bandwidth indicating strong correlations.

Theoretical models can reproduce the observed band structure with reasonable parameters.

Discrepancies with the simple t-J model highlight the importance of extended models.

Abstract

Recent angle resolved photoemission (ARPES) results for the insulating cuprate ${\rm Sr_2 Cu O_2 Cl_2}$ have provided the first experimental data which can be directly compared to the (theoretically) well--studied problem of a single hole propagating in an antiferromagnet. The ARPES results reported a small bandwidth, providing evidence for the existence of strong correlations in the cuprates. However, in the same experiment some discrepancies with the familiar 2D ${\rm t-J}$ model were also observed. Here we discuss a comparison between the ARPES results and the quasiparticle dispersion of both (i) the ${\rm t-t'-J}$ Hamiltonian and (ii) the three--band Hubbard model in the strong--coupling limit. Both model Hamiltonians show that the experimentally observed one--hole band structure can be approximately reproduced using reasonable values for ${\rm t'}$, or the direct oxygen hopping amplitude ${\rm t_{pp}}$.