2000/04/25 by Claudius Gros, Roser Valentí, Roser Valenti +3 · 3 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #cond-mat
paper · pdf · doi:10.1103/physrevb.62.r14617
published as Phys. Rev. B, Vol.62, R14 617 (2000)
arxiv created 2000/04/25 · openalex publication_date 2000/12/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Recent experimental evidence suggests the existence of three distinct V-valence states (V4+, V4.5+, and V5+) in the low-temperature phase of NaV2O5 in apparent discrepancy with the observed spin gap. We investigate a spin cluster model, consisting of weakly coupled, frustrated four-spin clusters aligned along the crystallographic b axis that was recently proposed to reconcile these experimental observations. We have studied the phase diagram and the magnon dispersion relation of this model using DMRG, exact diagonalization, and a cluster-operator theory. We find a spin gap for all parameter values and two distinct phases, a cluster phase and a Haldane phase. We evaluate the size of the gap and the magnon dispersion and find no parameter regime which would reproduce the experimental results. We conclude that this model is inappropriate for the low-temperature regime of NaV2O5.