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

Blai Casals, Andrea Schiaffino, Arianna Casiraghi, Sampo J. Hämäläinen, Diego López González, Sebastiaan van Dijken, Massimiliano Stengel, and Gervasi Herranz, Phys. Rev. Lett. 120, 217601. DOI: https://doi.org/10.1103/PhysRevLett.120.217601

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 440cm1, which was previously detected in IR experiments, but whose microscopic nature was unknown.

Oxides for new-generation electronics

  • Hits: 2048

INSTITUT DE CIÈNCIA DE MATERIALS DE BARCELONA, Copyright © 2020 ICMAB-CSIC | Privacy Policy | This email address is being protected from spambots. You need JavaScript enabled to view it.