The Spin-1 Heisenberg Antiferromagnet: New Results from Series Expansions

TL;DR

This paper uses series expansions to analyze the ground state properties and spectra of the spin-1 Heisenberg antiferromagnet with anisotropy, identifying phase transitions and comparing with spin-wave theory.

Contribution

It provides new, systematic results for ground state properties and spectra of the anisotropic spin-1 Heisenberg antiferromagnet on the square lattice, including phase transition locations.

Findings

Determined the quantum phase transition point in the easy-plane sector.

Calculated ground state energy, magnetization, and susceptibility with high accuracy.

Compared series expansion results with spin-wave theory, showing agreement and differences.

Abstract

We calculate ground state properties (energy, magnetization, susceptibility) and one-particle spectra for the $S = 1$ Heisenberg antiferromagnet with easy-axis or easy-plane single site anisotropy, on the square lattice. Series expansions are used, in each of three phases of the system, to obtain systematic and accurate results. The location of the quantum phase transition in the easy-plane sector is determined. The results are compared with spin-wave theory.