Charge correlations and optical conductivity in weakly doped antiferromagnets

TL;DR

This paper studies charge correlations and optical conductivity in weakly doped antiferromagnets using the t-J model, revealing that charge dynamics are driven by transitions between spin-bag quasiparticle states.

Contribution

It introduces a cumulant formalism within the Mori-Zwanzig approach to analyze charge and optical properties in the t-J model, aligning well with numerical results.

Findings

Spectra agree with exact diagonalization results

Charge dynamics driven by spin-bag quasiparticle transitions

Method explains features in correlation functions

Abstract

We investigate the dynamical charge-charge correlation function and the optical conductivity in weakly doped antiferromagnets using Mori-Zwanzig projection technique. The system is described by the two-dimensional t-J model. The arising matrix elements are evaluated within a cumulant formalism which was recently applied to investigate magnetic properties of weakly doped antiferromagnets. Within the present approach the ground state consists of non-interacting hole quasiparticles. Our spectra agree well with numerical results calculated via exact diagonalization techniques. The method we employ enables us to explain the features present in the correlation functions. We conclude that the charge dynamics at weak doping is governed by transitions between excited states of spin-bag quasiparticles.