2008/02/29 by Tigran Hakobyan
Physics and Astronomy · #Physics of Superconductivity and Magnetism #Quantum many-body systems #Theoretical and Computational Physics #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.78.012407
published as Phys. Rev. B 78, 012407 (2008) · 4 pages, some references updated and added, typos corrected, to appear in Phys. Rev. B
arxiv created 2008/06/25 · openalex publication_date 2008/07/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The Lieb-Mattis theorem is generalized to an antiferromagnetic spin-ladder model with four-spin cyclic exchange interaction. We prove that for J>2\phantom\rule0.3em0exK, the antiferromagnetic ordering of energy levels takes place separately in two sectors, which remain symmetric and antisymmetric under the reflection with respect to the longitudinal axis of the ladder. We prove also that at the self-dual point J=2\phantom\rule0.3em0exK, the Lieb-Mattis rule holds in the sectors with fixed number of rung singlets. In both cases, it agrees with the similar rule for Haldane chain with appropriate spin number.