van Hove Singularity effects in Strongly Correlated Fermions

TL;DR

This paper investigates how van Hove singularities influence the electronic properties of a two-dimensional Hubbard model, revealing doping-dependent effects on quasiparticle damping and resistivity relevant to cuprate superconductors.

Contribution

It demonstrates the persistence and pinning of van Hove singularities near the Fermi level in a strongly correlated model, and analyzes their impact on transport properties across doping types.

Findings

Van Hove singularity remains near the Fermi level for hole doping.

Resistivity and damping rate scale linearly with temperature at optimal doping.

Electron-doped systems show quadratic temperature dependence of resistivity.

Abstract

We examine the effects of a van Hove singularity (vHs) in the density of states (DOS) of a two dimensional, $t-t'-U$ Hubbard model within the local approximation. Within our approximation the non-interacting Fermi surface is always retained away from half-filling; and we find that the vHs in the DOS survives, and for hole doping is nearly "pinned" to the Fermi level due to the enhancement of the effective mass, $m^*$. We discuss the electron-hole asymmetry of this phenomena and its relevance to the electron and hole doped cuprates. At optimal (hole) doping, with the Fermi level at the vHs, we find that the single particle damping rate $\Gamma$, and the resistivity $\rho_{dc}$, scale as $T$ for moderately low temperatures ($T \gtrsim 100$K), while for the electron doped system $\Gamma $ and $\rho_{dc} \sim T^2$.