Diffuse magnetic neutron scattering in the highly frustrated double perovskite ${\text{Ba}}_2{\text{YRuO}}_6$

Journal Article · Mon Feb 23 00:00:00 EST 2015 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.91.054415· OSTI ID:1185787

Nilsen, Gøran. J. ^[1]; Thompson, Corey M. ^[2]; Ehlers, Georg ^[3]; Marjerrison, Casey A. ^[4]; Greedan, John E. ^[2]

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1. Inst. Laue-Langevin (ILL), Grenoble (France)
2. McMaster Univ., Hamilton, ON (Canada). Dept. of Chemistry and Chemical Biology. Brockhouse Inst. for Materials Research
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
4. McMaster Univ., Hamilton, ON (Canada). Dept. of Physics and Astronomy

Here we investigated diffuse magnetic scattering in the highly frustrated double perovskite Ba₂YRuO₆ using polarized neutrons. Consistent with previous reports, the material shows two apparent transitions at 47 and 36 K to an eventual type I face-centered-cubic magnetic ground state. The (100) magnetic reflection shows different behavior from the five other observed reflections upon heating from 1.8 K, with the former broadening well beyond the resolution limit near 36 K. Closer examination of the latter group reveals a small, but clear, increase in peak widths between 36 and 47 K, indicating that this regime is dominated by short-range spin correlations. Diffuse magnetic scattering persists above 47 K near the position of (100) to at least 200 K, consistent with strong frustration. Reverse Monte Carlo (RMC) modeling of the diffuse scattering from 45 to 200 K finds that the spin-spin correlations between nearest and next-nearest neighbors are antiferromagnetic and ferromagnetic, respectively, at temperatures near the upper ordering temperature, but both become antiferromagnetic and of similar magnitude above 100 K. The significance of this unusual crossover is discussed in light of the super-superexchange interactions between nearest and next-nearest neighbors in this material and the demands of type I order. The dimensionality of the correlations is addressed by reconstructing the scattering in the (hk0) plane using the RMC spin configurations. This indicates that one-dimensional spin correlations dominate at temperatures close to the first transition. In addition, a comparison between mean-field calculations and (hk0) scattering implies that further neighbor couplings play a significant role in the selection of the ground state. Finally, the results and interpretation are compared with those recently published for monoclinic Sr₂YRuO₆, and similarities and differences are emphasized.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1185787
• Alternate ID(s): OSTI ID: 1181397
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 91, Issue 5; ISSN 1098-0121
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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36 MATERIALS SCIENCE