Low Temperature Physics: 36, 522 (2010); https://doi.org/10.1063/1.3455792 (10 pages)
Физика Низких Температур: Том 36, Выпуск 6 (Июнь 2010), c. 654-654    ( к оглавлению , назад )

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
E-mail: sanina@mail.ioffe.ru

Received November 9, 2009

Аннотация

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;
PACS: 76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance;
PACS: 77.80.–e Ferroelectricity and antiferroelectricity.

Ключевые слова: multiferroic, ECMO, x-ray diffraction, dielectric and magnetic properties, conductivity.