Eur. Phys. J. B 31, 209-216 (2003)
https://doi.org/10.1140/epjb/e2003-00025-7

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

Institut für Theoretische Physik, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany

Corresponding author: ^a as@thp.uni-koeln.de

Received: 6 November 2002
Revised: 19 December 2002
Published online: 4 February 2003

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.