Polarization-Controlled Structural Modulation in the Single Atomic Layer at the PbZr<sub>0.2</sub>Ti<sub>0.8</sub>O<sub>3</sub>/LaNiO<sub>3</sub> Interface.

Hwang, Soo-Yoon; Lee, Sangjae; Disa, Ankit S; Visani, Cristina; Choi, Si-Young; Walker, Frederick J; Ahn, Charles H; Zhu, Yimei et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Conductivity modulation via ferroelectric polarization coupling with LaNiO<sub>3</sub> (LNO) is demonstrated at an epitaxial ferroelectric-LNO interface. Conductivity measurements, varying the thickness of the LNO channel, show that this phenomenon is confined to a few atomic layers at the interface. Combining <i>in situ</i> biasing and off-axis holography, we mapped out electrostatic potentials at the PbZr0<sub>.2</sub>Ti<sub>0.8</sub>O<sub>3</sub>(PZT)/LNO/SrTiO<sub>3</sub>(STO) heterostructure upon polarization switching. Using aberration-corrected STEM, the interfacial atomic structures were investigated for the two different PZT polarization states. Polarization in PZT induces a significant change in the in-plane O-Ni-O bond angles, with a 37° modulation in the topmost 1 or 2 LNO unit cells, driven by strain in the oxygen sublattice for the two opposite polarization directions in PZT. Both oxygen and cation sublattices exhibit strain responses exceeding 10% upon switching. This atomic-layer structural modulation highlights a mechanism for functional oxide heterostructure development, offering pathways for advancements in nonvolatile memory, sensors, and energy-efficient transistors.