We report spontaneous appearance of antiferromagnetic order in a model gapped quantum paramagnet Ni(Cl1−xBrx)2⋅4SC(NH2)2 induced by a change in bromine concentration x. This transition is qualitatively similar to a z = 1 magnetic quantum critical point. However, the observed critical scaling of thermodynamic and magnetic properties has rather unusual critical exponents.
@article{arxiv.1708.02776,
title = {Quantum criticality in a three dimensional spin system at zero field and pressure},
author = {K. Yu. Povarov and A. Mannig and G. Perren and J. S. Möller and E. Wulf and J. Ollivier and A. Zheludev},
journal= {arXiv preprint arXiv:1708.02776},
year = {2017}
}