Pulsed-field magnetization experiments (fields B of up to 85 T and temperatures T down to 0.4 K) are reported on nine organic Cu-based two-dimensional (2D) Heisenberg magnets. All compounds show a low-T magnetization that is concave as a function of B, with a sharp ``elbow'' transition to a constant value at a field Bc. Monte-Carlo simulations including a finite interlayer exchange energy J⊥ quantitatively reproduce the data; the concavity indicates the effective dimensionality and Bc is an accurate measure of the in-plane exchange energy J. Using these values and Ne\'el temperatures measured by muon-spin rotation, it is also possible to obtain a quantitative estimate of ∣J⊥/J∣. In the light of these results, it is suggested that in magnets of the form [Cu(HF2)(pyz)2]X, where X is an anion, the sizes of J and J⊥ are controlled by the tilting of the pyrazine (pyz) molecule with respect to the 2D planes.
@article{arxiv.0803.4169,
title = {Exchange parameters of copper-based quasi-two-dimensional Heisenberg magnets measured using high magnetic fields and muon-spin rotation},
author = {P. A. Goddard and J. Singleton and P. Sengupta and R. D. McDonald and T. Lancaster and S. J. Blundell and F. L. Pratt and S. Cox and N. Harrison and J. L. Manson and H. I. Southerland and J. A. Schlueter},
journal= {arXiv preprint arXiv:0803.4169},
year = {2008}
}