Differences in the quasiparticle dynamics for one-band and three-band cuprate models

TL;DR

This paper compares quasiparticle dynamics in one-band and three-band cuprate models, revealing fundamental differences that impact their suitability for describing underdoped cuprates.

Contribution

It demonstrates that one-band and three-band models exhibit qualitatively different quasiparticle behaviors, challenging their interchangeable use for cuprate physics.

Findings

Spin fluctuations and longer-range hopping are both essential in one-band models.

Spin fluctuations have minor effects in the three-band Emery model.

The models describe fundamentally different quasiparticles.

Abstract

We study the quasiparticles of the one-band $t$-$J$ and $t$-$t'$-$t"$-$J$ models using a variational approximation that includes spin fluctuations in the vicinity of the hole. We explain why the spin fluctuations and the longer range hopping have complementary contributions to the quasiparticle dynamics, and thus why both are essential to obtain a dispersion in agreement with that measured experimentally. This is very different from the three-band Emery model in the strongly-correlated limit, where the same variational approximation shows that spin fluctuations have a minor effect on the quasiparticle dynamics. This difference proves that these one-band and three-band models describe qualitatively different quasiparticles, and therefore they they cannot both be suitable to describe the physics of underdoped cuprates.