Excitations of anisotropic spin-1 chains with matrix product ground state

TL;DR

This paper studies the excitations in anisotropic spin-1 chains with known ground states, using numerical and analytical methods to understand their spectral properties and compare them with established models.

Contribution

It provides a detailed numerical and analytical analysis of low-lying excitations in anisotropic spin-1 chains with matrix product ground states, extending understanding beyond isotropic models.

Findings

Observation of spin liquid behavior with an excitation gap

Comparison of anisotropic and isotropic AKLT models

Quantitative analysis of the excitation gap using single mode approximation

Abstract

We investigate a large class of antiferromagnetic spin-1 chains with nearest neighbour interaction and exactly known matrix product ground state. The spectrum of low-lying excitations is calculated numerically by DMRG and exact diagonalisation. Spin liquid behaviour with an excitation gap is observed meeting the Haldane scenario. Further, we compare properties of the anisotropic model with the well-known isotropic AKLT model and use the analytical single mode approximation to obtain a quantitative understanding of the excitation gap. The low-lying excited states can be interpreted in terms of a magnon-like elementary excitation.