title: Coexistence of Three Ferroic Orders in the Multiferroic Compound [(CH3 )4 N][Mn(N3 )3 ] with Perovskite-Like Structure.
abstract: The perovskite azido compound [(CH3 )4 N][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 )4 N](+) 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 )4 N][Mn(N3 )3 ] is a singular material in which three ferroic orders coexist even above room temperature.
authors.affiliation: QuiMolMat Group, Department of Fundamental Chemistry and CICA, Faculty of Sciences, University of A Coruña, Campus A Coruña, 15071, A Coruña, Spain.
authors.forename: L Claudia
authors.identifier: 0000-0001-8822-0910
authors.initials: LC
authors.lastname: Gómez-Aguirre
authors.affiliation: QuiMolMat Group, Department of Fundamental Chemistry and CICA, Faculty of Sciences, University of A Coruña, Campus A Coruña, 15071, A Coruña, Spain.
authors.forename: Breogán
authors.identifier: 0000-0003-2302-8623
authors.initials: B
authors.lastname: Pato-Doldán
authors.affiliation: CNR-SPIN, 67100, L'Aquila, Italy.
authors.forename: Alessandro
authors.identifier: 0000-0003-1000-4745
authors.initials: A
authors.lastname: Stroppa
authors.affiliation: School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 430074, Wuhan, China.
authors.forename: Li-Ming
authors.initials: LM
authors.lastname: Yang
authors.affiliation: Bremen Center for Computational Materials Science, University of Bremen, Am Falturm 1, 28359, Bremen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Frauenheim
authors.affiliation: Department of Applied Physics, University of Santiago de Compostela, 15782, Santiago de Compostela, Spain.
authors.forename: Jorge
authors.identifier: 0000-0002-6024-6294
authors.initials: J
authors.lastname: Mira
authors.affiliation: Department of Applied Physics, University of Santiago de Compostela, 15782, Santiago de Compostela, Spain.
authors.forename: Susana
authors.identifier: 0000-0002-0314-8567
authors.initials: S
authors.lastname: Yáñez-Vilar
authors.affiliation: Department of Industrial Engineering II, University of A Coruña, Campus de Esteiro, 15403, Ferrol, Spain.
authors.forename: Ramón
authors.identifier: 0000-0003-2506-7263
authors.initials: R
authors.lastname: Artiaga
authors.affiliation: QuiMolMat Group, Department of Fundamental Chemistry and CICA, Faculty of Sciences, University of A Coruña, Campus A Coruña, 15071, A Coruña, Spain.
authors.forename: Socorro
authors.identifier: 0000-0003-1501-2410
authors.initials: S
authors.lastname: Castro-García
authors.affiliation: QuiMolMat Group, Department of Fundamental Chemistry and CICA, Faculty of Sciences, University of A Coruña, Campus A Coruña, 15071, A Coruña, Spain. msanchez@udc.es.
authors.forename: Manuel
authors.identifier: 0000-0002-3441-0994
authors.initials: M
authors.lastname: Sánchez-Andújar
authors.affiliation: QuiMolMat Group, Department of Fundamental Chemistry and CICA, Faculty of Sciences, University of A Coruña, Campus A Coruña, 15071, A Coruña, Spain. m.senaris.rodriguez@udc.es.
authors.forename: María Antonia
authors.initials: MA
authors.lastname: Señarís-Rodríguez
keywords: ab initio calculations; azides; ferroics; perovskites; phase transitions