Spins acting like real bar magnets in a new material


The dipolar force between magnetic moments is present in all magnetic systems. The lithium rare earth (RE) tetrafluorides, LiREF4 are an excellent testing ground for the physics of dipolar-coupled systems because the spins in this material behave like real bar magnets.

Scientists from the École Polytechnique Fédérale de Lausanne (EPFL), the Paul Scherrer Institute (PSI), the Helmholtz-Zentrum Berlin (HZB), the University of Chicago, the University College of London, Oak Ridge National Laboratory and the University of Bern have focused their research on an antiferromagnetic member of the family LiErF4 and addressed the magnetic order, the classical phase transition, and the transition and fluctuations about the quantum critical point. The experiments were supported by NMI3.

Magnetic structures of LiREF4 (courtesy of the authors) Magnetic structures of LiREF4 (courtesy of the authors)

Determining the magnetic structure

In order to determine the magnetic structure the team has performed neutron scattering, specific heat, and magnetic susceptibility studies at the HZB. Complementary measurements were performed at the Swiss neutron source SINQ at PSI. These experiments allowed the team to visualise that the arrangement of the spins in the material was antiferromagnetic.

Future implications

LiErF4 has the advantage of a simple, well-characterized Hamiltonian and of being available in large, high-quality single crystals. With the discovery of its properties, researchers now have a material that provides a perfect test bed for getting insights into the fundamental science of quantum dipolar antiferromagnetism.

NMI3 thanks Neda Nikseresht and Henrik Rønnow from the Laboratory of Quantum Magnetism, Switzerland, for reviewing this article.

Original publication

Kraemer C., Nikseresht N, Piatek J.O., Tsyrulin N., Piazza B., Kiefer K., Klemke B., Rosenbaum T.F., Aeppli G., Gannarelli C., Prokes K., Podlesnyak A., Strässle T., Keller T., Zaharko O., Krämer K.W., Rønnow H.M. (2012) Dipolar Antiferromagnetism and Quantum Criticality in LiErF4. Science, 336 (6087), 1416-1419.

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