Fig. 1: Structure of the Au/Cr/BSO/NSTO-based FTJs and ferroelectric properties of the 1-nm BSO films.
From: Giant tunnelling electroresistance in atomic-scale ferroelectric tunnel junctions
a Schematic illustration of the FTJ structure. b Atomic-level diagram of the Au (60 nm)/Cr (15 nm)/BSO (1 nm)/NSTO FTJ structure. While the Sm atoms are distributed randomly in the structure, we provide one possible BSO structure obtained from a previous study24. c The HAADF-STEM image of a BSO film grown on NSTO substrate, with the BSO thickness of ~1 nm. d The polarization hysteresis loop (left axis) and switching current (right axis) of the 1-nm BSO, obtained by the PUND-mode measurement under an electric field at 625 Hz frequency. e The out-of-plane phase of the PFM measurement, shown in color scale after a box-in-box writing with a tip bias in the 1-nm-thick BSO film. The entire detection area is 8 μm × 8 μm. The tip biasing is noted in the corresponding area, and the region without the note is unbiased. f Off-field local PFM measurements for BSO films with the thickness of 1 nm, including both phase (left axis) and amplitude (right axis) hysteresis loops.
