Reference : First-principles study of competing ferroelectric and antiferroelectric instabilities...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Physics
First-principles study of competing ferroelectric and antiferroelectric instabilities in BaTiO3/BaO superlattices
Bousquet, Eric mailto [Université de Liège - ULg > Département de physique > Physique théorique des matériaux >]
Junquera, Javier mailto [Universidad de Cantabria, Santander, Spain > Departamento de Ciencias de la Tiera y Fisica de la Materia Condensata > > >]
Ghosez, Philippe mailto [Université de Liège - ULg > Département de physique > Physique théorique des matériaux >]
Physical Review. B, Condensed Matter and Materials Physics
American Physical Society
Yes (verified by ORBi)
[en] We report a first-principles study of (BaTiO3) m/ (BaO) n superlattices for a wide range of periodicities m/n. We show that such a system develops a polar zone-center instability for sufficiently large m/n ratio, which can be understood, at least qualitatively, from a simple electrostatic model and should lead to a ferroelectric ground state. However, the analysis of the phonon-dispersion curves also points out the appearance of stronger antiferroelectric instabilities at the zone boundaries around m=4, before the critical ratio for ferroelectricity is
reached and which still dominate beyond it. The dominant character of the antiferroelectric instability is
explained from the depolarizing field which hardens the ferroelectric mode. This analysis allows us to predict
that, (BaTiO3) m/ (BaO) n superlattices should present an antiferroelectric ground state for m larger than 4, which should smoothly evolve to a multidomain structure for increasing m values and only become ferroelectric for large m.
Physique Théorique des Matériaux
EU-OxIDes (FP7), PAI-QCN (P6/42)
Researchers ; Professionals ; Students

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