Various series expansions for a Heisenberg antiferromagnet model for SrCu₂(BO₃)₂

1998/11/03 by Zheng Weihong, C. J. Hamer, J. Oitmaa · 1 citation
Physics and Astronomy · #cond-mat.str-el

paper · pdf · doi:10.1103/physrevb.60.6608

RevTeX, 13 figures

arxiv created 1998/11/03 · arxiv updated 2009/11/30

Abstract

We use a variety of series expansion methods at both zero and finite temperature to study an antiferromagnetic Heisenberg spin model proposed recently by Miyahara and Ueda for the quasi two-dimensional material SrCu₂(BO₃)₂. We confirm that this model exhibits a first-order quantum phase transition at T=0 between a gapped dimer phase and a gapless Néel phase when the ratio x=J'/J of nearest and next-nearest neighbour interactions is varied, and locate the transition at x_c=0.691(6). Using longer series we are able to give more accurate estimates of the model parameters by fitting to the high temperature susceptibility data.

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