Real‐Space Observation of Potential Reconstruction at Metallic/Insulating Oxide Interface

Abstract

Electric field reconstruction at interfaces plays a crucial role in device performances controlling, for example, Schottky potential barrier and interfacial Rashba effect. Here, scanning transmission electron microscopy (STEM) and ab‐initio calculation are used to estimate the atomic‐scale and large‐scale potential reconstruction at the interface between a metallic oxide SrRuO3 (SRO) thin film and an insulating DyScO3 (DSO) substrate. The intensity and the symmetry of the large‐scale electrostatic reconstruction at the interface is probed by 4D‐STEM discussing the center‐of‐mass shift for different angular ranges detection. Numerical simulations indicate that thermal diffuse scattered (TDS) electrons can be sensitive to large‐scale electric field and experiments based on these diffused electrons near the interface confirm that the electric field extends more in the insulating DyScO3 (DSO) side. The magnitude of the electrostatic drop at the interface estimated by the 4D‐STEM experiment is in accordance with the ab‐initio values for a p‐type reconstruction of the interface plane. Furthermore, an atomically resolved TDS potential asymmetry is observed in real‐space at the SRO/DSO interface by 4D‐STEM. This asymmetry is associated with the formation of a local ferroelectric type dipole at the interfacial unit‐cell revealing unambiguously the balance evolution between antiferrodistortive and ferroelectric instabilities at the interface between a metallic SRO and an insulating DSO.

Charge Distribution across Capped and Uncapped Infinite‐Layer Neodymium Nickelate Thin Films

“…By collecting the whole diffraction pattern at each pixel, one can obtain a high resolution real space atomic mapping with good oxygen contrast. [ 18,19 ] Here, in Figure 2E, by employing such an integrated Centre of Mass (iCOM) analysis by 4D‐STEM, we have a clear atomic‐level mapping including oxygen. It indicates periodic partial intercalation of apical oxygen in the IL crystalline structure.…”

Valence-Ordered Thin-Film Nickelate with Tri-component Nickel Coordination Prepared by Topochemical Reduction

“…4D-STEM data collected simultaneously with the HAADF images are shown in Figure c,f. Figure b corresponds to the displacement intensity of the center-of-mass (COM) of the diffraction plane collected at every probe position, and donut shapes reveal the presence of atomic columns at their centers, even for oxygen atoms. , Indeed, the lateral momentum transfer to the electron beam (Δ p ) is determined from these center-of-mass measurements. This Δ p is negatively proportional to the in-plane electric field E , thereby making Figure b a rough representation of in-plane electric field absolute intensity as well.…”

Direct Quantifying Charge Transfer by 4D-STEM: A Study on Perfect and Defective Hexagonal Boron Nitride

“…In recent years, CoM maps have been employed to study the polarization of III–V semiconductors like GaN, heterostructures involving SrTiO 3 , DyScO 3 and SrRuO 3 , as well as ferroelectric materials such as BiFeO 3 . ,− Compared to the conventional DPC technique, where the electric field is derived as the difference of intensity between two opposite quadrants of a segmented detector, − in 4D-STEM a more complete analysis can be made since the inhomogeneity of the intensity distribution in the CBED pattern is directly accessible. , …”