Kraemer, ConradinNikseresht, NedaPiatek, Julian O.Tsyrulin, NikolayDalla Piazza, BastienKiefer, KlausKlemke, BastianRosenbaum, Thomas F.Aeppli, GabrielGannarelli, CheProkes, KarelPodlesnyak, AndreyStraessle, ThierryKeller, LukasZaharko, OksanaKraemer, Karl W.Ronnow, Henrik M.2012-06-292012-06-292012-06-29201210.1126/science.1221878https://infoscience.epfl.ch/handle/20.500.14299/82436WOS:000305211700038Magnetism has been predicted to occur in systems in which dipolar interactions dominate exchange. We present neutron scattering, specific heat, and magnetic susceptibility data for LiErF4, establishing it as a model dipolar-coupled antiferromagnet with planar spin-anisotropy and a quantum phase transition in applied field H-c parallel to = 4.0 +/- 0.1 kilo-oersteds. We discovered non-mean-field critical scaling for the classical phase transition at the antiferromagnetic transition temperature that is consistent with the two-dimensional XY/h(4) universality class; in accord with this, the quantum phase transition at H-c exhibits three-dimensional classical behavior. The effective dimensional reduction may be a consequence of the intrinsic frustrated nature of the dipolar interaction, which strengthens the role of fluctuations.Ferromagnet Litbf4Phase-TransitionSpin BathLihof4FluctuationsTemperatureMagnetsLatticeOrderFieldtext::journal::journal article::research article