Spin and charge dynamics of the t-J model at intermediate electron densities: absence of spin-charge separation

TL;DR

This study uses exact diagonalization to analyze spin and charge dynamics in the 2D t-J model at intermediate densities, finding no evidence of spin-charge separation and supporting Fermi liquid behavior.

Contribution

It provides detailed numerical evidence that spin and charge excitations in the t-J model behave as particle-hole excitations, challenging the notion of spin-charge separation at these densities.

Findings

Correlation functions match Fermi liquid predictions

Deviations are due to symmetry-related selection rules

Low energy peaks originate from particle-hole excitations

Abstract

We present an exact diagonalization study of the dynamical spin and density correlation functions in small clusters of 2D t-J model for intermediate and low electron densities, rho<0.7. Both correlation functions agree remarkably well with the convolution of the single-particle spectral function, i.e. the simplest estimate within the Fermi liquid picture. Deviations from the convolution are shown to originate from symmetry-related selection rules, which are unaccounted for in the convolution estimate. Comparing the momentum distribution in the final states of the low lying spin and charge excitations to that of the ground state we establish that for all fillings under consideration the low energy peaks in both correlation functions originate from particle-hole excitations, as expected in a Fermi liquid.