Theory of the density fluctuation spectrum of strongly correlated electrons

TL;DR

This paper investigates the density fluctuation spectrum of strongly correlated electrons in the 2D t-J model, revealing the spin polaron nature of charge carriers and explaining anomalous features observed in numerical studies.

Contribution

It introduces a mixed gauge slave boson approach to analyze the density response, providing a natural explanation for low energy structures as coherent polaron motion.

Findings

Results agree with exact diagonalization data

Identifies low energy structures as spin polaron effects

Explains anomalous density response features

Abstract

The density response function $N(q,\omega)$ of the two-dimensional $t-J$ model is studied starting from a mixed gauge formulation of the slave boson approach. Our results for $N(q, \omega)$ are in remarkable agreement with exact diagonalization studies, and provide a natural explanation of the anomalous features in the density response in terms of the spin polaron nature of the charge carriers. In particular we have identified unexplained low energy structures in the diagonalization data as arising from the coherent polaron motion of holes in a spin liquid.