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arXiv · 1405.1527

First-order structural transition in the multiferroic perovskite-like formate [(CH3)2NH2][Mn(HCOO)3]

M. Sanchez-Andujar·L. C. Gomez-Aguirre·B. Pato Doldan·S. Yanez-Vilar·R. Artiaga·A. L. Llamas-Saiz·R. S. Manna·F. Schnelle·M. Lang·F. Ritter·A. A. Haghighirad·M. A. Senaris-Rodriguez
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Abstract

In this work we explore the overall structural behaviour of the [(CH3)2NH2][Mn(HCOO)3] multiferroic compound across the temperature range where its ferroelectric transition takes place by means of calorimetry, thermal expansion measurements and variable temperature powder and single crystal X-ray diffraction. The results clearly proof the presence of structural phase transition at Tt ~187 K (temperature at which the dielectric transition occurs) that involves a symmetry change from R-3c to Cc, twinning of the crystals, a discontinuous variation of the unit cell parameters and unit cell volume, and a sharp first-order-like anomaly in the thermal expansion. In addition, the calorimetric results show a 3-fold order-disorder transition. The calculated pressure dependence of the transition temperature is rather large (dTt/dP = 4.6 $\pm$ 0.1 K/kbar), so that it should be feasible to shift it to room temperature using adequate thermodynamic conditions, for instance by application of external pressure.

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M. Sanchez-Andujar, L. C. Gomez-Aguirre, B. Pato Doldan, S. Yanez-Vilar, R. Artiaga, A. L. Llamas-Saiz, R. S. Manna, F. Schnelle, M. Lang, F. Ritter, A. A. Haghighirad, M. A. Senaris-Rodriguez. 2014-05-07. First-order structural transition in the multiferroic perovskite-like formate [(CH3)2NH2][Mn(HCOO)3]. https://doi.org/10.1039/c3ce42411a

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