Kink Structure in the Quasiparticle Band of Doped Hubbard Systems

TL;DR

This paper identifies a kink in the quasiparticle spectrum of the 2D Hubbard model in the underdoped regime, linking it to short-range antiferromagnetic excitations, which may explain experimental observations in cuprates.

Contribution

It introduces a high-resolution self-consistent projection operator method to reveal the kink structure caused by magnetic excitations in doped Hubbard systems.

Findings

Kink structure observed in the quasiparticle spectrum.

Kink caused by mixing with short-range antiferromagnetic excitations.

Potential explanation for doping-dependent kink in cuprate superconductors.

Abstract

By making use of the self-consistent projection operator method with high-momentum and high-energy resolutions, we find a kink structure in the quasiparticle excitation spectrum of the two-dimensional Hubbard model in the underdoped regime. The kink is caused by a mixing between the quasiparticle state and excitations with short-range antiferromagnetic order. We suggest that this might be the origin of the strong concentration dependence of the 'kink' found in La_{2-x}Sr_{x}CuO_{4} (x=0.03-0.07).