Spin excitations and thermodynamics of the t-J model on the honeycomb lattice

TL;DR

This paper develops a Green-function theoretical approach to study spin excitations and thermodynamics in the t-J model on a honeycomb lattice, analyzing temperature and doping effects on magnetic properties.

Contribution

It introduces a spin-rotation-invariant Green-function method for the honeycomb lattice t-J model, providing new insights into its excitation spectrum and thermodynamic behavior.

Findings

Doping reduces antiferromagnetic short-range order.

Magnetic susceptibility varies with temperature and doping.

Results compared with square lattice t-J model show lattice-dependent differences.

Abstract

We present a spin-rotation-invariant Green-function theory for the dynamic spin susceptibility in the spin-1/2 antiferromagnetic t-J Heisenberg model on the honeycomb lattice. Employing a generalized mean-field approximation for arbitrary temperatures and hole dopings, the electronic spectrum of excitations, the spin-excitation spectrum and thermodynamic quantities (two-spin correlation functions, staggered magnetization, magnetic susceptibility, correlation length) are calculated by solving a coupled system of self-consistency equations for the correlation functions. The temperature and doping dependence of the magnetic (uniform static) susceptibility is ascribed to antiferromagnetic short-range order. Our results on the doping dependencies of the magnetization and susceptibility are analyzed in comparison with previous results for the t_J model on the square lattice.