Low-Temperature Dielectric Anisotropy Driven by an Antiferroelectric Mode in SrTiO3

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Details

Original languageEnglish
Article number217601
Pages (from-to)1-6
JournalPhysical Review Letters
Volume120
Issue number21
Publication statusPublished - 25 May 2018
MoE publication typeA1 Journal article-refereed

Researchers

Research units

  • CSIC
  • ICREA

Abstract

Strontium titanate (SrTiO3) is the quintessential material for oxide electronics. One of its hallmark features is the transition, driven by antiferrodistortive (AFD) lattice modes, from a cubic to a ferroelastic low-temperature phase. Here we investigate the evolution of the ferroelastic twin walls upon application of an electric field. Remarkably, we find that the dielectric anisotropy of tetragonal SrTiO3, rather than the intrinsic domain wall polarity, is the main driving force for the motion of the twins. Based on a combined first-principles and Landau-theory analysis, we show that such anisotropy is dominated by a trilinear coupling between the polarization, the AFD lattice tilts, and a previously overlooked antiferroelectric (AFE) mode. We identify the latter AFE phonon with the so-called "R mode" at ∼440 cm-1, which was previously detected in IR experiments, but whose microscopic nature was unknown.

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