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arXiv · 2011.03941

Diffraction by multipoles in a 5d2 rhenium double perovskite

S. W. Lovesey·D. D. Khalyavin·G. van der Laan·G. J. Nilsen
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Abstract

A recent polarized neutron diffraction experiment on the 5d2 rhenium double perovskite Ba2YReO6 held at a low temperature uncovered weak magnetic diffraction peaks. Data analysis inferred a significantly reduced Re dipole moment, and long-range order compatible with an antiferromagnet, non-collinear motif. To interpret the experimental findings, we present a model wavefunction for Re ions derived from the crystal field potential, Coulomb interaction, and spin-orbit coupling that fully respects the symmetry of the low-temperature ordered state. It is used to calculate in analytic form all multipole moments visible in neutron and resonance enhanced x-ray diffraction. A minimal model consistent with available neutron diffraction data predicts significant multipolar moments up to the hexadecapole, and, in particular, a dominant charge-like quadrupole moment. Calculated diffraction patterns embrace single crystal x-ray diffraction at the Re L-edge, and renewed neutron diffraction, to probe the presumed underlying multipolar order.

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S. W. Lovesey, D. D. Khalyavin, G. van der Laan, G. J. Nilsen. 2020-11-08. Diffraction by multipoles in a 5d2 rhenium double perovskite. https://doi.org/10.1103/physrevb.103.104429

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