Orbital order in classical models of transition-metal compounds

• Published in: Europhysics letters Vol. 67; no. 6; pp. 990 - 996
• Main Authors: Nussinov, Z, Biskup, M, Chayes, L, Brink, J. van den
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01-09-2004; EDP Sciences
• Subjects: 05.70.Fh; 71.20.Be; 75.30.Ds
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/epl/i2004-10134-5

We study the classical 120 degree and related orbital models. These are the classical limits of quantum models which describe the interactions among orbitals of transition-metal compounds. We demonstrate that at low temperatures these models exhibit a long-range order which arises via an “order by disorder” mechanism. This strongly indicates that there is orbital ordering in the quantum version of these models, notwithstanding recent rigorous results on the absence of spin order in these systems.