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Magnetic multipoles in a ruthenate Ca3Ru2O7

DOI: 10.1103/PhysRevB.99.134444 DOI Help

Authors: S. W. Lovesey (Diamond Light Source) , D. D. Khalyavin (ISIS Facility) , G. Van Der Laan (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 99 , PAGES 134444

State: Published (Approved)
Published: April 2019

Abstract: Compulsory Dirac multipoles in the bilayer perovskite Ca3Ru2O7 are absent in published analyses of experimental data. In a first step at correcting knowledge of the magnetic structure, we have analyzed existing Bragg diffraction patterns gathered on samples held well below the NĂ©el temperature at which A-type antiferromagnetic order of axial dipoles spontaneously develops. Patterns were gathered with neutrons, and linearly polarized x rays tuned in energy to a ruthenium atomic resonance. Neutron diffraction data contain solid evidence of Dirac dipoles (anapoles or toroidal moments). No such conclusion is reached with existing x-ray diffraction data, which instead is ambiguous on the question. To address this shortcoming by future experiments, we calculated additional diffraction patterns. Chiral order of Dirac multipoles is allowed by magnetic space-group PCna21, and it can be exposed in Bragg diffraction using circularly polarized x rays. Likewise, a similar experiment can expose a chiral order of axial dipoles. A magnetic field applied parallel to the b axis creates a ferrimagnetic structure in which bulk magnetization arises from field-induced nonequivalent Ru sites (magnetic space-group Pmc21).

Journal Keywords: Bragg difraction; anapoles; toroidal moments

Diamond Keywords: Antiferromagnetism

Subject Areas: Physics, Materials, Mathematics

Technical Areas: Theoretical Physics

Added On: 30/04/2019 09:58

Discipline Tags:

Materials Science Metallurgy Perovskites Quantum Materials Physics Magnetism Mathematics

Technical Tags: