title: Realization of a three-dimensional spin-anisotropic harmonic honeycomb iridate.
abstract: Spin and orbital quantum numbers play a key role in the physics of Mott insulators, but in most systems they are connected only indirectly--via the Pauli exclusion principle and the Coulomb interaction. Iridium-based oxides (iridates) introduce strong spin-orbit coupling directly, such that these numbers become entwined together and the Mott physics attains a strong orbital character. In the layered honeycomb iridates this is thought to generate highly spin-anisotropic magnetic interactions, coupling the spin to a given spatial direction of exchange and leading to strongly frustrated magnetism. Here we report a new iridate structure that has the same local connectivity as the layered honeycomb and exhibits striking evidence for highly spin-anisotropic exchange. The basic structural units of this material suggest that a new family of three-dimensional structures could exist, the 'harmonic honeycomb' iridates, of which the present compound is the first example.
authors: 1] Pulsed Field Facility, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA [2] Department of Physics, University of Texas, Austin, Texas 78712, USA.
authors: K A
authors: KA
authors: Modic
authors: 1] Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Physics, University of California, Berkeley, California 94720, USA.
authors: Tess E
authors: TE
authors: Smidt
authors: Department of Physics, University of California, Berkeley, California 94720, USA.
authors: Itamar
authors: I
authors: Kimchi
authors: 1] Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Physics, University of California, Berkeley, California 94720, USA.
authors: Nicholas P
authors: NP
authors: Breznay
authors: Physics Department, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
authors: Alun
authors: A
authors: Biffin
authors: Physics Department, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
authors: Sungkyun
authors: S
authors: Choi
authors: Physics Department, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
authors: Roger D
authors: RD
authors: Johnson
authors: Physics Department, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK.
authors: Radu
authors: R
authors: Coldea
authors: Department of Chemistry, The University of Texas at Dallas, Richardson, Texas 75080, USA.
authors: Pilanda
authors: P
authors: Watkins-Curry
authors: Department of Chemistry, The University of Texas at Dallas, Richardson, Texas 75080, USA.
authors: Gregory T
authors: GT
authors: McCandless
authors: Department of Chemistry, The University of Texas at Dallas, Richardson, Texas 75080, USA.
authors: Julia Y
authors: JY
authors: Chan
authors: Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors: Felipe
authors: F
authors: Gandara
authors: Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors: Z
authors: Z
authors: Islam
authors: 1] Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Physics, University of California, Berkeley, California 94720, USA.
authors: Ashvin
authors: A
authors: Vishwanath
authors: Pulsed Field Facility, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors: Arkady
authors: A
authors: Shekhter
authors: Pulsed Field Facility, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors: Ross D
authors: RD
authors: McDonald
authors: 1] Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Physics, University of California, Berkeley, California 94720, USA.
authors: James G
authors: JG
authors: Analytis