title: Anisotropic Exchange within Decoupled Tetrahedra in the Quantum Breathing Pyrochlore Ba_{3}Yb_{2}Zn_{5}O_{11}.
abstract: The low energy spin excitation spectrum of the breathing pyrochlore Ba_{3}Yb_{2}Zn_{5}O_{11} has been investigated with inelastic neutron scattering. Several nearly resolution limited modes with no observable dispersion are observed at 250 mK while, at elevated temperatures, transitions between excited levels become visible. To gain deeper insight, a theoretical model of isolated Yb^{3+} tetrahedra parametrized by four anisotropic exchange constants is constructed. The model reproduces the inelastic neutron scattering data, specific heat, and magnetic susceptibility with high fidelity. The fitted exchange parameters reveal a Heisenberg antiferromagnet with a very large Dzyaloshinskii-Moriya interaction. Using this model, we predict the appearance of an unusual octupolar paramagnet at low temperatures and speculate on the development of intertetrahedron correlations.
authors.affiliation: Department of Physics and Astronomy, University of Waterloo, Ontario N2L 3G1, Canada.
authors.forename: J G
authors.initials: JG
authors.lastname: Rau
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: L S
authors.initials: LS
authors.lastname: Wu
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: A F
authors.initials: AF
authors.lastname: May
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.|Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA.
authors.forename: L
authors.initials: L
authors.lastname: Poudel
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: B
authors.initials: B
authors.lastname: Winn
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: V O
authors.initials: VO
authors.lastname: Garlea
authors.affiliation: Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: A
authors.initials: A
authors.lastname: Huq
authors.affiliation: Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: P
authors.initials: P
authors.lastname: Whitfield
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Taylor
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Lumsden
authors.affiliation: Department of Physics and Astronomy, University of Waterloo, Ontario N2L 3G1, Canada.|Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, Canada.|Canadian Institute for Advanced Research, 180 Dundas Street West, Suite 1400, Toronto, Ontario M5G 1Z8, Canada.
authors.forename: M J P
authors.initials: MJ
authors.lastname: Gingras
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.|Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37966, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Christianson