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Structural invariance upon antiferromagnetic ordering in geometrically frustrated swedenborgite, CaBaCo 2 Fe 2 O 7
Author(s) -
Reim J. D.,
Rosén E.,
Schweika W.,
Meven M.,
Leo N. R.,
Meier D.,
Fiebig M.,
Schmidt M.,
Kuo C.Y.,
Pi T.W.,
Hu Z.,
Valldor M.
Publication year - 2014
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576714023528
Subject(s) - antiferromagnetism , neutron diffraction , frustration , powder diffraction , single crystal , materials science , crystallography , stoichiometry , condensed matter physics , diffraction , geometrical frustration , neutron , hexagonal phase , chemistry , crystal structure , hexagonal crystal system , optics , physics , organic chemistry , quantum mechanics
Centimetre‐sized single crystals of high‐quality CaBaCo 2 Fe 2 O 7 were synthesized by the optical floating zone technique. The metal‐to‐metal stoichiometry and oxygen content were confirmed by spectroscopy and thermal reduction experiments. The hexagonal symmetry P 6 3 mc (No. 186) well describes the powder X‐ray and neutron diffraction as well as single‐crystal neutron diffraction at all measured temperatures. This symmetry is also consistent with optical second harmonic generation data obtained between 10 and 295 K. However, a satisfactory structure description from single‐crystal neutron diffraction data needs an oxygen split position. Specific heat, magnetic susceptibility and powder neutron diffraction data indicate a magnetic phase transition at T N = 159 K to an antiferromagnetic ground state, but with a persisting hexagonal symmetry and intrinsic geometric frustration.