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Neutron Laue diffraction study of the complex low‐temperature magnetic behaviour of brownmillerite‐type Ca 2 Fe 2 O 5
Author(s) -
Auckett Josie E.,
McIntyre Garry J.,
Avdeev Maxim,
De Bruyn Hank,
Tan Thiam Teck,
Li Sean,
Ling Chris D.
Publication year - 2015
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/s1600576714027976
Subject(s) - brownmillerite , antiferromagnetism , neutron diffraction , magnetic susceptibility , crystallography , magnetic structure , condensed matter physics , magnetic moment , crystal structure , anomaly (physics) , diffraction , chemistry , materials science , magnetic field , magnetization , physics , perovskite (structure) , optics , quantum mechanics
The atomic and magnetic structure of brownmillerite Ca 2 Fe 2 O 5 has been refined against single‐crystal neutron Laue diffraction data collected at 300, 100 and 10 K under zero‐field and low‐magnetic field (35 Oe = 35 × 10 3 /4π A m −1 ) conditions. Ca 2 Fe 2 O 5 is a canted G‐type antiferromagnet with Pcm ′ n ′ symmetry, the magnetic moments on Fe being directed approximately along the crystallographic c axis at room temperature. The refinement results show clearly that this magnetic structure persists down to T = 10 K, despite a previous suggestion that an anomalous magnetic susceptibility enhancement observed in Ca 2 Fe 2 O 5 single crystals between 40 and 140 K might signify a reorientation of the antiferromagnetic easy axis from c to a below 40 K. Alternative explanations for this susceptibility anomaly are considered in terms of the evidence for partial or short‐range loss of order in the anomalous regime, possibly due to the presence of multiple competing sublattice interactions.