Fig. 3
From: Artificial two-dimensional polar metal at room temperature
Polar displacements. a ABF-STEM image of 10BTO/3STO/3LTO along [110] direction. b, c Enlarged images of red rectangular areas in a showing atomic positions of Ba, Sr, La, Ti, and O ions across interfaces. Gray arrows (in b–d) indicate the reversal directions of Ti–O polar displacements. d Experimentally layer-resolved Ti–O polar displacements in a 10BTO/3STO/3LTO superlattice. Here the Ti–O polar displacements (or ΔTi–O) are defined as oxygen displacement with respect to Ti along the out-of-plane. The error bar shows the standard deviations of the averaged measurements for each vertical atomic layer. e Theoretically layer-resolved Ti–O polar displacements in a 4BTO/3STO/2LTO superlattice. Black and gray arrows indicate negative and zero slopes of the Ti–O displacements, respectively, in BTO layers, whereas blue ellipses highlight positive slopes in LTO layers
