Centrosymmetry Breaking and Ferroelectricity Driven by Short-Range Magnetic Order in the Quadruple Perovskite (YMn3)Mn4O12

• Published in: Inorganic chemistry 2019-10, Vol.58 (20), p.14204-14211
• Main Authors: Verseils, Marine, Mezzadri, Francesco, Delmonte, Davide, Cabassi, Riccardo, Baptiste, Benoît, Klein, Yannick, Calestani, Gianluca, Bolzoni, Fulvio, Gilioli, Edmondo, Gauzzi, Andrea
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.9b02298

By means of single-crystal X-ray diffraction, we give direct crystallographic evidence of a centrosymmetry breaking below T S = 200 K, concomitant with the onset of a commensurate structural modulation in the quadruple perovskite YMn3Mn4O12. This result, which explains the anomalously large thermal coefficient of the Y3+ ion in previously reported structural models, is attributed to the small size of the Y3+ ion, which causes its underbonding within the dodecahedral coordination polyhedron. The present data are consistent with a commensurate superstructure described by an I-centered pseudo-orthorhombic cell with polar Ia symmetry and a ≈ a F√2 = 10.4352(7) Å, b ≈ 2b F = 14.6049(9) Å, c ≈ c F√2 = 10.6961(7) Å, and β = 90.110(3)°, where a F ≈ c F ≈ 7.45 Å, b F ≈ 7.34 Å, and β ≈ 91° are the unit cell parameters of the I2/m structure observed at room temperature. Consistent with the above polar structure, at lower temperature, T* = 70 K, we observe in polycrystalline samples an anomaly of the direct current (DC) and alternating current (AC) magnetization, concomitant with the appearance of a net electric polarization, as indicated by pyrocurrent and dielectric constant measurements. These results, complemented by electrical transport measurements, suggest a magnetic ferroelectricity driven by short-range magnetic order in YMn3Mn4O12.