Precursor phenomenon on ferroelectric transition in multiferroic YMn2O5 |
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| Authors: | Isao Kagomiya Ken-ichi Kakimoto Hitoshi Ohsato |
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| Affiliation: | 1. Laboratoire de Physique des Solides, Université Paris-Sud, CNRS-UMR 8502, 91405 Orsay, France;2. Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA;1. SPCTS, CNRS, ENSCI, Université de Limoges, CEC, 12 Rue Atlantis, 87068 Limoges, France;2. ADEME, 20 Avenue du Grésillé, BP 90406, 49004 Angers Cedex 1, France;3. CNRS, Université de Bordeaux, ICMCB, 87 Avenue du docteur Schweitzer, F-33608 Pessac, France;1. Science des Procédés Céramiques et de Traitements de Surface (SPCTS), CNRS UMR 7315, ENSCI, Université de Limoges, Centre Européen de la Céramique (CEC), 12 rue Atlantis, 87068, LIMOGES Cedex, France;2. Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan;3. Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan;4. Sorbonne Universités, UPMC Univ Paris 06, UMR 8233 CNRS, 4 Place Jussieu, 75005, Paris, France;1. Hubei province Key Laboratory of Science in Metallurgical Process, Wuhan University of Science and Technology, Wuhan 430081, China;2. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China |
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| Abstract: | Series of RMn2O5 (R = Sm-Lu, Bi, Y) are simultaneously ferroelectric and antiferromagnetic at low temperatures. The ferroelectric Curie temperature (TCE = 25–40 K) is slightly lower than the antiferromagnetic Néel temperature (TN = ～45 K), implying that the ferroelectricity is induced with the antiferromagnetic long-range order in RMn2O5. Previously, we have investigated the thermal expansion anomaly in YMn2O5 at higher temperatures than TN = 45 K, which would be the precursor phenomenon relating to the ferroelectric transition. This study tries to investigate a further detailed precursor phenomenon to make clear the origin of the ferroelectricity in YMn2O5. Particularly, we focus on the temperature factors of each cation in the temperature range from 50 K to 170 K. The single crystal X-ray diffraction of YMn2O5 was integrated at 298 K and 112 K by using a single crystal diffractometer with an imaging plate. The structural parameters were well refined as Pbam at both temperatures. In the refined result, it was found that the thermal ellipsoid became more anisotropic for the Mn or the Y ions with decreasing temperature from 298 K to 112 K. In addition, the long principal axis of the thermal ellipsoids rotated in the a–b plane with decrease of temperature. At 112 K, the long principal axis of Mn3+ thermal ellipsoid in a–b plane is almost parallel to the direction from the apex to the base of the pyramid square. The direction agrees with a possible ionic displacement speculated from the irreducible representation analysis. |
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