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Bragg diffraction by a magnetic all-in–all-out configuration with application to a cubic cerium pyrochlore oxide

DOI: 10.1103/PhysRevB.106.224408 DOI Help

Authors: S. W. Lovesey (ISIS Facility; Diamond Light Source; Oxford University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 106

State: Published (Approved)
Published: December 2022

Abstract: The Bragg diffraction of neutrons and x rays are well suited to the task of determining the distribution of magnetization in crystals. Applications of the two techniques proceed by contrasting observed intensities with intensities calculated with a specific model, and changing the model as need be to achieve satisfactory agreement. An all-in–all-out (AIAO) magnetic configuration of magnetic dipoles on a cubic face-centered lattice with networks of corner-sharing tetrahedra is often mentioned in the context of pyrochlore oxides, for example, but the corresponding neutron and x-ray-diffraction patterns appear to not have been calculated. Our results for patterns of Bragg spots from an AIAO magnetic configuration defined by a magnetic space group are symmetry informed and yield exact reflection conditions. Specifically, a long-range order of magnetic dipoles is forbidden in our model. Bulk properties arise from higher-order multipoles that include quadrupoles and octupoles. Bragg spots that exclude all magnetic multipoles other than an octupole have been discovered, and they can be observed by both neutron diffraction and resonant x-ray diffraction. All magnetic multipoles allowed in diffraction by cerium ions ( 4 f 1 ) are presented in terms of coefficients in a well-documented and unusual magnetic ground state. Symmetry of the cerium site in the cubic structure constrains the coefficients. Our scattering amplitudes have an application in both neutron- and x-ray diffraction experiments on Ce 2 Zr 2 O 7 , for example, and searches for the sought-after cerium octupole. Also presented for future use is a result for the total, energy-integrated magnetic neutron-scattering intensity by a powder sample.

Subject Areas: Materials, Physics

Technical Areas:

Added On: 15/12/2022 09:48

Discipline Tags:

Physics Magnetism Materials Science

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