title: Dimensional Reduction in Quantum Dipolar Antiferromagnets.
abstract: We report ac susceptibility, specific heat, and neutron scattering measurements on a dipolar-coupled antiferromagnet LiYbF_{4}. For the thermal transition, the order-parameter critical exponent is found to be 0.20(1) and the specific-heat critical exponent -0.25(1). The exponents agree with the 2D XY/h_{4} universality class despite the lack of apparent two-dimensionality in the structure. The order-parameter exponent for the quantum phase transitions is found to be 0.35(1) corresponding to (2+1)D. These results are in line with those found for LiErF_{4} which has the same crystal structure, but largely different T_{N}, crystal field environment and hyperfine interactions. Our results therefore experimentally establish that the dimensional reduction is universal to quantum dipolar antiferromagnets on a distorted diamond lattice.
authors.affiliation: Laboratory for Quantum Magnetism, Institute of Condensed Matter Physics (ICMP), Ecole Polytechnique Féderale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Babkevich
authors.affiliation: Laboratory for Quantum Magnetism, Institute of Condensed Matter Physics (ICMP), Ecole Polytechnique Féderale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Jeong
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Laboratory for Quantum Magnetism, Institute of Condensed Matter Physics (ICMP), Ecole Polytechnique Féderale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: I
authors.initials: I
authors.lastname: Kovacevic
authors.affiliation: Laboratory for Quantum Magnetism, Institute of Condensed Matter Physics (ICMP), Ecole Polytechnique Féderale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.|ICFP, Département de physique, École normale supérieure, 45 rue d'Ulm, 75005 Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Finco
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Toft-Petersen
authors.affiliation: Institut Laue-Langevin, BP 156, F-38042, Grenoble Cedex 9, France.
authors.forename: C
authors.initials: C
authors.lastname: Ritter
authors.affiliation: Laboratory for Quantum Magnetism, Institute of Condensed Matter Physics (ICMP), Ecole Polytechnique Féderale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.|Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen, Switzerland.|Department of Materials and Nanophysics, KTH Royal Institute of Technology, SE-164 40 Kista, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Månsson
authors.affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Nakatsuji
authors.affiliation: Laboratory for Quantum Magnetism, Institute of Condensed Matter Physics (ICMP), Ecole Polytechnique Féderale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: H M
authors.initials: HM
authors.lastname: Rønnow