Eur. Phys. J. B 16, 7-10 (2000)
https://doi.org/10.1007/s100510070242

On the origin of biquadratic exchange in spin 1 chains

¹ Laboratoire de Physique Quantique, Université Paul Sabatier, 31062 Toulouse Cedex, France
² Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221, USA

Corresponding author: ^a mila@irsamc2.ups-tlse.fr

Received: 4 January 2000
Published online: 15 July 2000

Abstract

One-dimensional spin 1 systems may have a rich phase diagram including Haldane gap and dimerized phases if the usually very small biquadratic exchange becomes significant. We show that this unlikely condition may be fulfilled in electron systems with quasi-degenerate orbitals. This mechanism may have been experimentally realized in the spin 1 chain LiVGe₂O₆. The implications for the exploration of the physics and quantum chemistry of spin 1 chains are discussed.