Browsing by Author "Manjón-Sanz, A"

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    Competing magnetic interactions and the role of unpaired 4f llectrons in oxygen-deficient perovskites Ba3RFe2O7.5 (R = Y, Dy)
    (American Chemical Society (ACS), 2023-05-01) Brown, AJ; Avdeev, M; Manjón-Sanz, A; Brand, HEA; Ling, CD
    Oxygen-deficient perovskite compounds with the general formula Ba3RFe2O7.5 present a good opportunity to study competing magnetic interactions between Fe3+ 3d cations with and without the involvement of unpaired 4f electrons on R3+ cations. From analysis of neutron powder diffraction data, complemented by ab initio density functional theory calculations, we determined the magnetic ground states when R3+ = Y3+ (non-magnetic) and Dy3+ (4f9). They both adopt complex long-range ordered antiferromagnetic structures below TN = 6.6 and 14.5 K, respectively, with the same magnetic space group Ca2/c (BNS #15.91). However, the dominant influence of f-electron magnetism is clear in temperature dependence and differences between the size of the ordered moments on the two crystallographically independent Fe sites, one of which is enhanced by R-O-Fe superexchange in the Dy compound, while the other is frustrated by it. The Dy compound also shows evidence for temperature- and field-dependent transitions with hysteresis, indicating a field-induced ferromagnetic component below TN. © 2024 American Chemical Society