Charge dynamics in magnetically disordered Mott insulators

TL;DR

This paper investigates charge dynamics in disordered Mott insulators using semi-analytical and numerical methods, revealing Gaussian tails in the Hubbard band instead of sharp edges.

Contribution

It provides new insights into the spectral density and charge gap in disordered Mott insulators derived from the $t$-$J$ model, especially in the limit of small exchange coupling.

Findings

Absence of sharp edges in the Hubbard band

Gaussian tails appear in the spectral density

Charge gap behavior in disordered Mott insulators

Abstract

With the aid of both a semi-analytical and a numerically exact method we investigate the charge dynamics in the vicinity of half-filling in the one- and two-dimensional $t$-$J$ model derived from a Fermi-Hubbard model in the limit of large interaction $U$ and hence small exchange coupling $J$. The spin degrees of freedom are taken to be disordered. So we consider the limit $0 < J \ll T \ll W$ where $W$ is the band width. We focus on evaluating the spectral density of a single hole excitation and the charge gap which separates the upper and the lower Hubbard band. One of the key findings is the evidence for the absence of sharp edges of the Hubbard band, instead Gaussian tails appear.