Unusual ferroelectric and magnetic phases in multiferroic 2H-BaMnO.sub.3./sub. ceramics

0476185 - FZÚ 2018 RIV US eng J - Journal Article
Kamba, Stanislav - Nuzhnyy, Dmitry - Savinov, Maxim - Toledano, P. - Laguta, Valentyn - Brázda, Petr - Palatinus, Lukáš - Kadlec, Filip - Borodavka, Fedir - Kadlec, Christelle - Bednyakov, Petr - Bovtun, Viktor - Kempa, Martin - Kriegner, D. - Drahokoupil, Jan - Kroupa, Jan - Prokleška, J. - Chapagain, K. - Dabrowski, B. - Goian, Veronica
Unusual ferroelectric and magnetic phases in multiferroic 2H-BaMnO₃ ceramics.
Physical Review B. Roč. 95, č. 17 (2017), s. 1-13, č. článku 174103. ISSN 2469-9950. E-ISSN 2469-9969
R&D Projects: GA MŠMT(CZ) LH15122; GA ČR GA15-08389S; GA ČR GA13-11473S; GA ČR GP14-14122P
Institutional support: RVO:68378271
Keywords : phase transition * soft mode * multiferroic
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 3.813, year: 2017

The structural phase transition in hexagonal BaMnO3 occurring at T-C = 130 K was studied in ceramic samples using electron and x-ray diffraction, second harmonic generation, as well as by dielectric and lattice dynamic spectroscopies. The low-temperature phase (space group P6(3)cm) is ferroelectric with a triplicated unit cell. The phase transition is driven by an optical soft mode from the Brillouin-zone boundary [q = (1/3, 1/3,0)], this mode activates in infrared and Raman spectra below T-C and it hardens according to the Cochran law. Upon cooling below T-C, the permittivity exhibits an unusual linear increase with temperature, below 60 K, in turn, a frequency-dependent decrease is observed, which can be explained by slowing down of ferroelectric domain wall motions.
Permanent Link: http://hdl.handle.net/11104/0272712