Open AccessMagnetic Structures of Mn11Ta4O21 and Interpretation as an Hexagonal A-site Manganite
Author(s) -
Cintli Aguilar-Maldonado,
E.P. Arévalo-López,
C. Ritter,
Olivier Mentré,
Ángel M. ArévaloLópez
Publication year - 2020
Publication title -
inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 233
eISSN - 1520-510X
pISSN - 0020-1669
DOI - 10.1021/acs.inorgchem.0c01387
Subject(s) - ferrimagnetism , manganite , antiferromagnetism , chemistry , neutron diffraction , octahedron , crystallography , ionic radius , stacking , hexagonal crystal system , magnetic structure , condensed matter physics , ferromagnetism , magnetization , crystal structure , ion , magnetic field , physics , organic chemistry , quantum mechanics
Mn 11 Ta 4 O 21 is presented as the first hexagonal A-site manganite. Based on simple rules, the structure is compatible with a 14H-layer ( cchchch ) 2 stacking sequence that is related to BaVO 3 and BaCrO 3 high-pressure polymorphs. The A-site overstoichiometry is explained through difference in ionic radii sizes between Ba and Mn. Magnetic properties show two transitions a T N1 = 88 K and T N2 = 56 K. Neutron powder diffraction evidence two magnetic structures with purely antiferromagnetic and ferrimagnetic orders below T N1 and T N2 , respectively. A complementary description with 14H-( hh ) 2 sequence of only Mn octahedra provides a direct comparison with BaMnO 3-δ hexagonal perovskites and naturally explains the AFM order. Below T N2 a magneto-elastic coupling along with uniaxial negative thermal expansion are observed.
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