Structural Properties of Two-Dimensional Strontium Titanate: A First-Principles Investigation

Motivated by the experimental synthesis of two-dimensional (2D) perovskite materials, we study the stability of 2D SrTiO${}_3$ from first principles. We find that the TiO${}_6$ octahedral rotations emerge in 2D SrTiO${}_3$ with a rotation angle twice that in the 3D bulk. The rotation angle decreases significantly with the film thickness, reflecting the strong interlayer coupling that is absent in the conventional 2D materials. Using the molecular dynamics simulations, the cubic-like phase is found to appear above 1000 K that is much higher than the transition temperature of 3D SrTiO${}_3$.