We study an extended Shastry-Sutherland model for SrCu_2(BO_3)_2 and analyze the low lying parts of the energy spectrum by means of a perturbative unitary transformation based on flow equations. The derivation of the 1-magnon dispersion (elementary triplets) is discussed. Additionally, we give a quantitative description (symmetries and energies) of bound states made from two elementary triplets. Our high order results allow to fix the model parameters for 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. To our knowledge this is the first quantitative treatment of bound states in a true 2d model.
@article{arxiv.cond-mat/0009403,
title = {SrCu_2(BO_3)_2 - a Two Dimensional Spin Liquid},
author = {Christian Knetter and Alexander Buehler and Erwin Mueller-Hartmann and Goetz S. Uhrig},
journal= {arXiv preprint arXiv:cond-mat/0009403},
year = {2016}
}
Comments
4 pages, 3 figures, Proceeding paper of the HFM2000 conference in Waterloo, Canada, Jun 2000