Canted Antiferromagnetism on Rectangular Layers of Fe2+ in Polymorphic CaFeSeO.
Kwing To LaiAlexander Christoph KomarekMaria Teresa Fernández-DíazPi-Shan ChangSungjoon HuhHelge RosnerChang-Yang KuoZhiwei HuTun-Wen PiPeter AdlerVadim KsenofontovLiu Hao TjengMartin ValldorPublished in: Inorganic chemistry (2017)
From stoichiometric amounts of CaO, Fe, and Se, pure powders and single crystals of quaternary [Formula: see text] can be obtained by solid-state reaction and self-flux growth, respectively. The as-synthesized compound exhibits a polymorphic crystal structure, where the two modifications have different stacking sequences of [Formula: see text] layers. The two polymorphs have similar unit cells but different crystal symmetries (Cmc21 and Pnma), of which the former is non-centrosymmetric. Fe is divalent (d6) and high-spin, as proven by X-ray spectroscopy, Mössbauer spectroscopy, and powder neutron diffraction data. The latter two, in combination with magnetic susceptibility and specific heat data, reveal a long-range antiferromagnetic spin order (TN = 160 K) with a minor spin canting. CaFeSeO is an electronic insulator, as confirmed by resistivity measurements and density functional theory calculations. The latter also suggest a relatively small energy difference between the two polymorphs, explaining their intimate intergrowth.
Keyphrases
- density functional theory
- solid state
- crystal structure
- molecular dynamics
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