Improper ferroelectrics

Levanyuk, A. P.; Sannikov, D. G.

doi:10.1070/pu1974v017n02abeh004336

Cited by 225 publications

(210 citation statements)

References 29 publications

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“…The symmetry constrains that are verified here correspond exactly to those that are observed in displacive systems like NaNO 2 , SC(NH 2 ) 2 or BCCD. [47][48][49] Consequently, similar to these systems, this part of the free energy density can be written as:…”

Section: The Critical Behaviour Of the Different Rmno 3 Compoundsmentioning

confidence: 99%

Landau model for the phase diagrams of the orthorhombic rare-earth manganitesRMnO3(R=Eu, Gd, Tb, Dy, Ho)

Ribeiro

Vieira

2010

Phys. Rev. B

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The present work aims to describe, within a single phenomenological approach, the specific sequence of phase transitions observed in the rare-earth manganites RMnO 3 at zero magnetic field. It is shown that a single integrated description of the temperature versus composition phase diagrams of these compounds and related solid solutions can be obtained within the scope of Landau theory by adopting the so called type-II description of the modulated phases. 75.85.+t, 64.70.Rh, 75.47.Lx,

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Section: The Critical Behaviour Of the Different Rmno 3 Compoundsmentioning

confidence: 99%

Landau model for the phase diagrams of the orthorhombic rare-earth manganitesRMnO3(R=Eu, Gd, Tb, Dy, Ho)

Ribeiro

Vieira

2010

Phys. Rev. B

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“…Such compounds in which the polarization appears as a slave of another non-polar primary order parameter with which it couples through a term linear in P is called an improper ferroelectric [105]. In contrast to the strain coupling in Eq.…”

Section: Improper and Hybrid Improper Ferroelectricsmentioning

confidence: 99%

Novel magneto-electric multiferroics from first-principles calculations

Varignon

Bristowe

Bousquet

et al. 2015

Comptes Rendus. Physique

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Interest in first-principles calculations within the multiferroic community has been rapidly on the rise over the last decade. Initially considered as a powerful support to explain experimentally observed behaviours, the trend has evolved and, nowadays, density functional theory calculations has become also an essential predicting tool for identifying original rules to achieve multiferroism and design new magneto-electric compounds. This chapter aims to highlight the key advances in the field of multiferroics for which first-principles methods have contributed significantly. The essential theoretical developments that made this search possible are also briefly presented.To cite this article: J. Varignon, N. C. Bristowe, E. Bousquet and Ph. Ghosez, C. R. Physique # (2014). RésuméNouveaux matériaux multiferroïques à partir de calculs de premiers principes.L'intérêt pour les calculs ab initio dans la communauté des multiferroïques n'a cessé de croître au cours de la dernière décennie. Initialement considérés comme un support efficace pour expliquer les comportements observés expérimentalement, la tendance a évolué et, actuellement, les calculs réalisés dans le cadre de la théorie de la fonctionnelle de la densité apparaissent aussi comme un outil prédictif incontournable permettant d'identifier de nouvelles voies pour parvenir au multiferroïsme et créer de nouveaux matériaux magnéto-électriques. Ce chapitre vise à présenter quelques avancées clefs dans le domaine des multiferroïques, auxquelles les méthodes ab initio ont conbribué de manière significative. Les développements théoriques essentiels ayant permis ces avancées sont aussi brièvement discutés.

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“…As known [21][22][23][24] the validity of the Landau method depends on the magnitude of the fluctuations in the system whose probability, according to the Boltzmann's principle, is proportional to exp(−F η {V,V }/k B T ). In the present paper we propose a test according to which the method is applicable to the considered problem if the root-mean-square fluctuations of the OP near the TS in the film of the thickness equal to the bifurcation length are small compared with the characteristic OP difference (η s − η l ).…”

Section: Fluctuations In Nanosystemsmentioning

confidence: 99%

Thermodynamic Stability of Transition States in Nanosystems

Umantsev

2009

J Stat Phys

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We present a theory which shows that, in a closed system of fixed volume capable of undergoing a phase transition, the transition state can be thermodynamically stable against the bulk phases if a certain material parameters criterion is fulfilled. In a small system below the critical size the transition state turns into a globally stable phase that can be observed experimentally. This effect is analogous to stabilization of icosahedral structures in clusters of certain sizes and energies. Stabilization of the transition state in small systems of limited resources allows us to conjecture that, in the case of a melting/freezing transition in pure substances, this state corresponds to an amorphous phase. Although unstable in open systems, this phase may be observed experimentally due to slow kinetics of its decomposition at low temperatures. The material-parameters criterion should help experimenters select the materials for the experimental verification of the phenomenon. In the present paper we consider thin films where the phase separation is permitted only parallel to the plane of the film. The calculations, however, hold true for 3D small systems: e.g., nanoparticles.

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Improper ferroelectrics

Cited by 225 publications

References 29 publications

Landau model for the phase diagrams of the orthorhombic rare-earth manganitesRMnO3(R=Eu, Gd, Tb, Dy, Ho)

Landau model for the phase diagrams of the orthorhombic rare-earth manganitesRMnO3(R=Eu, Gd, Tb, Dy, Ho)

Novel magneto-electric multiferroics from first-principles calculations

Thermodynamic Stability of Transition States in Nanosystems

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