title: Strange magnetic multipoles and neutron diffraction by an iridate perovskite (Sr2IrO4).
abstract: A theoretical investigation of a plausible construct for electronic structure in iridate perovskites demonstrates the existence of magnetic multipoles hitherto not identified. The strange multipoles, which are parity-even, time-odd and even rank tensors, are absent from the so-called j(eff) = 1/2 model. We prove that the strange multipoles contribute to magnetic neutron diffraction, and we estimate their contribution to intensities of Bragg spots for Sr(2)IrO(4). The construct encompasses the j(eff) = 1/2 model, and it is consistent with the known magnetic structure, ordered magnetic moment, and published resonant x-ray Bragg diffraction data. Over and above time-odd quadrupoles and hexadecapoles, whose contribution changes neutron Bragg intensities by an order of magnitude, according to our estimates, are relatively small triakontadipoles recently proposed as the primary magnetic order-parameter of Sr(2)IrO(4).
authors: ISIS Facility, STFC, Didcot, Oxfordshire OX11 0QX, UK. Diamond Light Source Ltd, Didcot, Oxfordshire OX11 0DE, UK.
authors: S W
authors: SW
authors: Lovesey
authors: D D
authors: DD
authors: Khalyavin