Fig. 2: Intercalated buffer layer as 180° domain wall in Bi2TeO5 single crystal.
From: Continuously tunable ferroelectric domain width down to the single-atomic limit in bismuth tellurite
a Lateral PFM images showing the striped FE domain in Bi2TeO5. b Atomically resolved HAADF-STEM image of typical 180° domain wall. The purple and orange circles denote Bi3+ and Te4+ atoms, respectively. Each row is labelled as either A (Bi column) or B (mixed Bi/Te column) row accordingly. Note that additional B row is intercalated (labelled in red and highlighted by white dashed rectangle) and act as a buffer layer in the switch of polarization. c Extracted DBi and θ in b. The error bars correspond to the standard deviation of DBi and θ. d Superposition of Bi3+ displacement vectors with b. e Colored ion displacements mapping in d. f Schematic structure of 180° domain wall. The blue and orange pyramids correspond to the opposite displacements of BiO5 cages. The buffered B-row is marked by the black dotted square.
