MnTaO2N: Polar LiNbO3‐type Oxynitride with a Helical Spin Order1. Issue 2 (21st November 2014)

• Record Type: Journal Article
• Authors: 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
• Is Part Of: Angewandte Chemie international edition. Volume 54:Issue 2(2015)
• Page Start: 516
• Page End: 521
• Publication Date: 2014-11-21
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201408483
• Languages: English
• ISSNs: 1433-7851

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The synthesis, structure, and magnetic properties of a polar and magnetic oxynitride MnTaO₂N 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 MnTaO₂N adopts the LiNbO₃‐type structure, with a random distribution of O²⁻ and N³⁻ anions. MnTaO₂N with an "orbital‐inactive" Mn²⁺ ion (d⁵; <italic>S</italic>=5/2) exhibits a nontrivial helical spin order at 25 K with a propagation vector of [0, 0, δ] (<italic>δ</italic>≈0.3), which is different from the conventional G‐type order observed in other orbital‐inactive perovskite oxides and LiNbO₃‐type oxides. This result suggests the presence of strong frustration because of the heavily tilted MnO₄N₂ octahedral network combined with the mixed O²⁻/N³⁻ species that results in a distribution of (super)‐superexchange interactions.</p> </abstract>