title: Mössbauer study of temperature-dependent cycloidal ordering in BiFeO3 nanoparticles.
abstract: To study the effects of different temperatures and particle sizes on the anharmonic cycloidal spin structure in BiFeO3 nanoparticles, Mössbauer spectroscopy was applied to three sets of particles with different mean diameters in the range of 54 nm to 1.6 μm at temperatures between 4.2 and 800 K. The paramagnetic transition showed a distinct broadening upon decreasing particle size with Néel temperatures decreasing from 652 to 631 K. The anharmonicity of the long-range cycloidal structure, calculated from experimental Mössbauer spectra, is revealed to decrease upon rising temperature, starting at 150-200 K and reaching the harmonic state at about 400 K.
authors.affiliation: Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen , 47048 Duisburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Landers
authors.forename: S
authors.initials: S
authors.lastname: Salamon
authors.forename: M
authors.initials: M
authors.lastname: Escobar Castillo
authors.forename: D C
authors.initials: DC
authors.lastname: Lupascu
authors.forename: H
authors.initials: H
authors.lastname: Wende
keywords: Bismuth ferrite; Mössbauer spectroscopy; anharmonic spin structure; long-range ordering; multiferroic; nanoparticles