Low Temperature Physics: 36, 522 (2010); https://doi.org/10.1063/1.3455792 (10 pages)
Charge carrier self-organization in ferroelectromagnetic semiconductors Eu0.8Ce0.2Mn2O5
E.I. Golovenchits, V.A. Sanina, V.G. Zalesskii, and M.P. Scheglov
A.F. Ioffe Physical Technical Institute of the RAS, 26 Politekhnicheskaya, St. Petersburg 194021, Russia
Received November 9, 2009
The state with a giant permittivity (ε΄ ~ 104) and ferromagnetism has been observed above 185 K (including room temperature) in single crystals of diluted semiconductor manganite–ferroelectromagnetic Eu0.8Ce0.2Mn2O5 in the investigations of x-ray diffraction, dielectric and magnetic properties, conductivity. X-ray diffraction study has revealed a layered superstructure along the c axis at room temperature. A model of the state with a giant ε΄ including as-grown 2D layers with doping impurities, charge carriers, and double-exchange coupled Mn3+–Mn4+ ion pairs is suggested. At low temperatures these layers form isolated electrically neutral small-size 1D superlattices, in which de Haas van Alphen oscillations were observed. As temperature grows and hopping conductivity increases, the charge carrier self-organization in the crystal cause formation of a layered superstructure consisting of charged layers (with an excess Mn3+ concentration) alternating with dielectric layers of the initial crystal — the ferroelectricity state due to charge ordering. Ferromagnetism results from double exchange between Mn3+ and Mn4+ ions through of charge carriers in the charged layers.
PACS: 75.47.Lx Magnetic oxides;
Key words: multiferroic, ECMO, x-ray diffraction, dielectric and magnetic properties, conductivity.