Coexistence of Three Ferroic Orders in the Multiferroic Compound [(CH3)4N][Mn(N3)3] with Perovskite‐Like Structure |
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| Authors: | Dr L Claudia Gómez‐Aguirre Dr Breogán Pato‐Doldán Dr Alessandro Stroppa Dr Li‐Ming Yang Prof Thomas Frauenheim Prof Jorge Mira Dr Susana Yáñez‐Vilar Dr Ramón Artiaga Dr Socorro Castro‐García Dr Manuel Sánchez‐Andújar Prof María Antonia Señarís‐Rodríguez |
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| Institution: | 1. QuiMolMat Group, Department of Fundamental Chemistry and CICA, Faculty of Sciences, University of A Coru?a, A Coru?a, Spain;2. CNR-SPIN, L'Aquila, Italy;3. School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, China;4. Bremen Center for Computational Materials Science, University of Bremen, Bremen, Germany;5. Department of Applied Physics, University of Santiago de Compostela, Santiago de Compostela, Spain;6. Department of Industrial Engineering II, University of A Coru?a, Ferrol, Spain |
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| Abstract: | The perovskite azido compound (CH3)4N]Mn(N3)3], which undergoes a first‐order phase change at Tt=310 K with an associated magnetic bistability, was revisited in the search for additional ferroic orders. The driving force for such structural transition is multifold and involves a peculiar cooperative rotation of the MnN6] octahedral as well as order/disorder and off‐center shifts of the (CH3)4N]+ cations and bridging azide ligands, which also bend and change their coordination mode. According to DFT calculations the latter two give rise to the appearance of electric dipoles in the low‐temperature (LT) polymorph, the polarization of which nevertheless cancels out due to their antiparallel alignment in the crystal. The conversion of this antiferroelectric phase to the paraelectric phase could be responsible for the experimental dielectric anomaly detected at 310 K. Additionally, the structural change involves a ferroelastic phase transition, whereby the LT polymorph exhibits an unusual and anisotropic thermal behavior. Hence, (CH3)4N]Mn(N3)3] is a singular material in which three ferroic orders coexist even above room temperature. |
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| Keywords: | ab initio calculations azides ferroics perovskites phase transitions |
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