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Article Dans Une Revue Physical Review B Année : 2017

Unusual ferroelectric and magnetic phases in multiferroic 2H-BaMnO3 ceramics

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1
Stanislav Kamba
  • Fonction : Auteur
Dmitry Nuzhnyy
  • Fonction : Auteur
Maxim Savinov
  • Fonction : Auteur
Valentin Laguta
  • Fonction : Auteur
Petr Brazda
  • Fonction : Auteur
Lukas Palatinus
Filip Kadlec
  • Fonction : Auteur
Fedir Borodavka
  • Fonction : Auteur
Christelle Kadlec
  • Fonction : Auteur
Petr Bednyakov
  • Fonction : Auteur
Viktor Bovtun
  • Fonction : Auteur
Martin Kempa
  • Fonction : Auteur
Dominik Kriegner
  • Fonction : Auteur
Jan Drahokoupil
  • Fonction : Auteur
Jan Kroupa
  • Fonction : Auteur
Jan Prokleska
  • Fonction : Auteur
Kamal Chapagain
  • Fonction : Auteur
Bogdan Dabrowski
  • Fonction : Auteur
Veronica Goian
  • Fonction : Auteur

Résumé

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. Based on our data we could not distinguish whether the high-temperature phase is paraelectric or polar (space groups P6(3)/mmc or P6(3)mc, respectively). Both variants of the phase transition to the ferroelectric phase are discussed based on the Landau theory. Electron paramagnetic resonance and magnetic susceptibility measurements reveal an onset of one-dimensional antiferromagnetic ordering below approximate to 220K which develops fully near 140 K and, below T-N approximate to 59 K, it transforms into a three-dimensional antiferromagnetic order.

Dates et versions

hal-03623445 , version 1 (29-03-2022)

Identifiants

Citer

Stanislav Kamba, Dmitry Nuzhnyy, Maxim Savinov, Pierre Toledano, Valentin Laguta, et al.. Unusual ferroelectric and magnetic phases in multiferroic 2H-BaMnO3 ceramics. Physical Review B, 2017, 95 (17), ⟨10.1103/PhysRevB.95.174103⟩. ⟨hal-03623445⟩

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