Metal organic magnets have enormous potential to host a variety of electronic and magnetic phases that originate from a strong interplay between the spin, orbital and lattice degrees of freedom. We control this interplay in the quantum magnet CuF2(D2O)2pyz by using high pressure to drive the system through a structural and magnetic phase transition. Using neutron scattering, we show that the low pressure state, which hosts a two-dimensional square lattice with spin-wave excitations and a dominant exchange coupling of 0.89 meV, transforms at high pressure into a one-dimensional spin-chain hallmarked by a spinon continuum and a reduced exchange interaction of 0.43 meV. This direct microscopic observation of a magnetic dimensional crossover as a function of pressure opens up new possibilities for studying the evolution of fractionalised excitations in low dimensional quantum magnets and eventually pressure-controlled metal--insulator transitions.
@article{arxiv.1708.03586,
title = {Dimensional reduction by pressure in the magnetic framework material CuF$_{2}$(D$_{2}$O)$_{2}$pyz: from spin-wave to spinon excitations},
author = {M. Skoulatos and M. Månsson and C. Fiolka and K. W. Krämer and J. Schefer and J. S. White and Ch. Rüegg},
journal= {arXiv preprint arXiv:1708.03586},
year = {2017}
}