Room temperature ferroelectricity in multiferroic HoMnO3 ceramics

• Published in: Physica. B, Condensed matter Vol. 407; no. 12; pp. 2072 - 2077
• Main Authors: Rout, P.P., Pradhan, S.K., Das, S.K., Roul, B.K.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.06.2012; Elsevier
• Subjects: Ceramics; Condensed matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectric; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Distortion; Domain structure; hysteresis; Exact sciences and technology; Ferroelectric materials; Ferroelectricity; Ferroelectricity and antiferroelectricity; Hysteresis loops; Origins; Photoelectron spectroscopy; Physics; Sintering; X-ray diffraction; X-ray diffraction; Ferroelectricity; Ceramics; Dielectric; Photoelectron spectroscopy; Photoelectron spectra; XRD; Holmium Molybdates; Ferroic material; Sintering; Dielectric losses; Microstructure; Exchange interactions; Ferroelectric hysteresis
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2012.02.007

We have observed good ferroelectric loops at room temperature in hexagonal HoMnO3 (HMO) bulk ceramics sintered at 1250°C. Microstructure and ferroelectric hysteresis loops are observed to be dependent on sintering temperature. It is observed that with an increase of sintering temperature, hexagonal a-axis is compressed and c-axis is marginally dilated with overall contraction of the hexagonal unit-cell volume. We explain the origin of ferroelectricity through relative movement of Ho ion and Mn ion within its unit-cell volume, resulting in the distortion of unit-cell volume. We argue that ferroelectric origin of hexagonal HMO at room temperature may be due to the marginal displacement of Ho ion along a-axis, that influences the exchange interaction among the Mn3+ and Ho3+ ions, causing magnetically induced ferroelectricity at room temperature.