Canted Antiferromagnetism on Rectangular Layers of Fe2+ in Polymorphic CaFeSeO

Kwing To Lai, Alexander Christoph Komarek, Maria Teresa Fernández-Díaz, Pi Shan Chang, Sungjoon Huh, Helge Rosner, Chang Yang Kuo, Zhiwei Hu, Tun Wen Pi, Peter Adler, Vadim Ksenofontov, Liu Hao Tjeng, Martin Valldor*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

From stoichiometric amounts of CaO, Fe, and Se, pure powders and single crystals of quaternary Ca2[FeSe2/2O2/2] 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 2[FeSe2/2O2/2]2- 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.

Original languageEnglish
Pages (from-to)4271-4279
Number of pages9
JournalInorganic Chemistry
Volume56
Issue number8
DOIs
StatePublished - 17 Apr 2017

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