We report an extraordinary pressure dependence of the magnetic interactions in the metal-organic system [(CuF2(H2O)2)2pyrazine]. At zero pressure, this material realizes a quasi-two-dimensional (Q2D) spin-1/2 square-lattice Heisenberg antiferromagnet. By high-pressure, high-field susceptibility measurements we show that the dominant exchange parameter is reduced continuously by a factor of 2 upon compression. Above 18 kbar, a phase transition occurs, inducing an orbital re-ordering that switches the dimensionality, transforming the Q2D lattice into weakly coupled chains (Q1D). We explain the microscopic mechanisms for both phenomena by combining detailed x-ray and neutron diffraction results with quantitative modeling using spin-polarized density functional theory.
@article{arxiv.1606.08344,
title = {Giant pressure dependence and dimensionality switching in a metal-organic quantum antiferromagnet},
author = {Björn Wehinger and Christoph Fiolka and Arianna Lanza and Rebecca Scatena and Mariusz Kubus and Audrey Grockowiak and William A. Coniglio and David Graf and Markos Skoulatos and Jyong-Hao Chen and Jan Gukelberger and Nicola Casati and Oksana Zaharko and Piero Macchi and Karl W. Krämer and Stan Tozer and Christopher Mudry and Bruce Normand and Christian Rüegg},
journal= {arXiv preprint arXiv:1606.08344},
year = {2018}
}
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