title: All-in-all-Out Magnetic Order and Propagating Spin Waves in Sm_{2}Ir_{2}O_{7}.
abstract: Using resonant magnetic x-ray scattering we address the unresolved nature of the magnetic ground state and the low-energy effective Hamiltonian of Sm_{2}Ir_{2}O_{7}, a prototypical pyrochlore iridate with a finite temperature metal-insulator transition. Through a combination of elastic and inelastic measurements, we show that the magnetic ground state is an all-in-all-out (AIAO) antiferromagnet. The magnon dispersion indicates significant electronic correlations and can be well described by a minimal Hamiltonian that includes Heisenberg exchange [J=27.3(6)  meV] and Dzyaloshinskii-Moriya interactions [D=4.9(3)  meV], which provides a consistent description of the magnetic order and excitations. In establishing that Sm_{2}Ir_{2}O_{7} has the requisite inversion symmetry preserving AIAO magnetic ground state, our results support the notion that pyrochlore iridates may host correlated Weyl semimetals.
authors.affiliation: London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Donnerer
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, OX1 3PU, United Kingdom.
authors.forename: M C
authors.initials: MC
authors.lastname: Rahn
authors.affiliation: ESRF-The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9, France.
authors.forename: M Moretti
authors.initials: MM
authors.lastname: Sala
authors.affiliation: London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.|Laboratory for Quantum Magnetism, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: J G
authors.initials: JG
authors.lastname: Vale
authors.affiliation: London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.|Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Pincini
authors.affiliation: Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Strempfer
authors.affiliation: ESRF-The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9, France.
authors.forename: M
authors.initials: M
authors.lastname: Krisch
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, OX1 3PU, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Prabhakaran
authors.affiliation: Department of Physics, University of Oxford, Clarendon Laboratory, Oxford, OX1 3PU, United Kingdom.
authors.forename: A T
authors.initials: AT
authors.lastname: Boothroyd
authors.affiliation: London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
authors.forename: D F
authors.initials: DF
authors.lastname: McMorrow