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MnTaO 2 N: Polar LiNbO 3 ‐type Oxynitride with a Helical Spin Order
Author(s) -
Tassel Cédric,
Kuno Yoshinori,
Goto Yoshihiro,
Yamamoto Takafumi,
Brown Craig M.,
Hester James,
Fujita Koji,
Higashi Masanobu,
Abe Ryu,
Tanaka Katsuhisa,
Kobayashi Yoji,
Kageyama Hiroshi
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201408483
Subject(s) - superexchange , octahedron , neutron diffraction , crystallography , type (biology) , condensed matter physics , magnetic structure , chemistry , polar , order (exchange) , perovskite (structure) , spin (aerodynamics) , frustration , spin structure , materials science , physics , crystal structure , ferromagnetism , antiferromagnetism , magnetization , magnetic field , ecology , finance , quantum mechanics , astronomy , economics , biology , thermodynamics
Abstract The synthesis, structure, and magnetic properties of a polar and magnetic oxynitride MnTaO 2 N are reported. High‐pressure synthesis at 6 GPa and 1400 °C allows for the stabilization of a high‐density structure containing middle‐to‐late transition metals. Synchrotron X‐ray and neutron diffraction studies revealed that MnTaO 2 N adopts the LiNbO 3 ‐type structure, with a random distribution of O 2− and N 3− anions. MnTaO 2 N with an “orbital‐inactive” Mn 2+ ion (d 5 ; S =5/2) exhibits a nontrivial helical spin order at 25 K with a propagation vector of [0,0,δ] ( δ ≈0.3), which is different from the conventional G‐type order observed in other orbital‐inactive perovskite oxides and LiNbO 3 ‐type oxides. This result suggests the presence of strong frustration because of the heavily tilted MnO 4 N 2 octahedral network combined with the mixed O 2− /N 3− species that results in a distribution of (super)‐superexchange interactions.