Dispersion and Symmetry of Bound States in the Shastry-Sutherland Model

Preprint

19 May 2000

preprint
Published by arXiv in arXiv

https://doi.org/10.48550/arXiv.cond-mat/0005322

Abstract

Bound states made from two triplet excitations on the Shastry-Sutherland (ShaSu) lattice are investigated. Based on the perturbative unitary transformation by flow equations quantitative properties like dispersions and qualitative properties like symmetries are determined. The high order results (up to (J_2/J_1)^{14}) permit to fix the parameters of SrCu_2(BO_3)_2 precisely: J_1=6.16(10)meV, x:=J_2/J_1=0.603(3), J_\perp=1.3(2)meV. At the border of the magnetic Brillouin zone (MBZ) a general double degeneracy is derived. An unexpected instability in the triplet channel at x=0.63 indicates a first order transition towards a triplet condensate, related to classical helical order.

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Version 1, 2000-05-19, ArXiv
Published version: Physical Review Letters, 85 (18), 3958.

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