paper

First-principles study of competing ferroelectric and antiferroelectric instabilities in BaTiO3/BaO superlattices

arXiv:1004.4028 · doi:10.1103/PhysRevB.82.045426

Abstract

We report a first-principles study of (BaTiO)/(BaO) superlattices for a wide range of periodicities . We show that such a system develops a polar zone-center instability for sufficiently large \textit{m}/\textit{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 , before the critical ratio for ferroelectricity is reached and which still dominate beyond it. The dominant character of the anti-ferroelectric instability is explained from the depolarizing field which hardens the ferroelectric mode. This analysis allows us to predict that, (BaTiO)/(BaO) superlattices should present an antiferroelectric ground state for larger than 4, which should smoothly evolve to a multidomain structure for increasing values and only become ferroelectric for large .

References in corpus (3)

Cited by in corpus (13)