Abstract:

Structural, morphological, magnetic, and electrical properties of the challenging Sr1-xBaxMnO3 (x=0, 0.4) manganite are discussed. Polycrystalline Sr1-xBaxMnO3 samples were prepared via the standard solid-state reaction. Conventional X-ray diffraction and synchrotron radiation measurements showed the hexagonal structure (space group P63/mmc) of the samples. The stability of the hexagonal symmetry of Sr0.6Ba0.4MnO3 persisted up to 120 K. This result, along with the fact that the space group P63/mmc is centrosymmetric, discounted the possibility of having a long-range ferroelectric ordering. Pristine SrMnO3 samples exhibited an antiferromagnetic transition at a Néel temperature ∼280 K. In turn, Sr0.6Ba0.4MnO3 showed two transitions at ∼325 K and ∼270 K. Measurements of the electrical polarization versus the electric field showed closed loops, although visually distinct from those of a true ferroelectric material. Hence it was evident that spurious effects caused the polarization curves that resembled ferroelectric loops. Resistivity measurements on Sr0.6Ba0.4MnO3 showed the insulating nature of these samples.

Website