65 research outputs found
Low Symmetry Phase in (001) BiFeO Epitaxial Constrained Thin Films
The lattice of (001)-oriented BiFeO epitaxial thin film has been
identified by synchrotron x-ray diffraction. By choosing proper scattering
zones containing the fixed (001) reflection, we have shown that low-symmetry
phases similar to a phase exist in the thin film at room temperature.
These results demonstrate a change in phase stability from rhombohedral in bulk
single crystals, to a modified monoclinic structure in epitaxial thin films
Electromagnon excitations in modulated multiferroics
The phenomenological theory of ferroelectricity in spiral magnets presented
in [M. Mostovoy, Phys. Rev. Lett. 96, 067601 (2006)] is generalized to describe
consistently states with both uniform and modulated-in-space ferroelectric
polarizations. A key point in this description is the symmetric part of the
magnetoelectric coupling since, although being irrelevant for the uniform
component, it plays an essential role for the non-uniform part of the
polarization. We illustrate this importance in generic examples of modulated
magnetic systems: longitudinal and transverse spin-density wave states and
planar cycloidal phase. We show that even in the cases with no uniform
ferroelectricity induced, polarization correlation functions follow to the soft
magnetic behavior of the system due to the magnetoelectric effect. Our results
can be easily generalized for more complicated types of magnetic ordering, and
the applications may concern various natural and artificial systems in
condensed matter physics (e.g., magnon properties could be extracted from
dynamic dielectric response measurements).Comment: 5 page
PEROVSKITE TYPE SEIGNETTOMAGNETS
Nous avons donné une rapide revue des recherches expérimentales et théoriques de l'institut Karpov pour la synthèse et l'étude des ferromagnétiques de type perovskites.A short review of exprimental and theoretical investigations of Karpov Institute in the synthesis and study of perovskite type seignettomagnets has been given
Modulated charged defects and conduction behaviour in doped BiFeO 3 thin films
10.1088/0022-3727/42/16/162001Journal of Physics D: Applied Physics4216-JPAP
CRYSTAL STRUCTURE AND PROPERTIES OF NEW CADMIUMAND THALLIUM-CONTAINING PEROVSKITES
De nouveaux composés du type pervoskite à base de cadmium et de thallium ont été synthétisés. Une étude aux rayons X et des mesures de propriétés diélectriques ont été réalisées. Il a été possible de conclure qu'ils sont caractérisables par leur polarisation spontanée.New cadmium- and thallium-containing perovskites have been synthesized. A X-ray study and some dielectric measurements have been fulfilled. It has been concluded that a spontaneously-polarized characterizes their
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