Direct visualization of interfacial defect effects on polarization switching in BaTiO₃ tunnel junctions.

Authors

Jeehun Jeong, Jinho Byun, Xiaoshan Xu, Alexei Gruverman, Jaekwang Lee, Sang Ho Oh

Published in

Science advances. Volume 12. Issue 38. Pages eaeh5401. Sep 18, 2026. Epub Sep 16, 2026.

Abstract

Deterministic control of polarization switching at complex oxide interfaces is essential for high-performance ferroelectric devices, yet the microscopic competition between external fields and polarization response remains difficult to probe directly. Combining atomic-scale scanning transmission electron microscopy and electron energy loss spectroscopy with in-situ biasing, we establish an asymmetric interfacial pinning mechanism in epitaxial Pt/BaTiO₃/La_2/3Sr_1/3MnO₃ ferroelectric tunnel junctions. At the Pt/BaTiO₃ interface, an oxygen vacancy-rich pinning layer induces Ti reduction and a strong, uniform downward electric field. In contrast, the BaTiO₃/La_2/3Sr_1/3MnO₃ boundary is characterized by localized La_Mn antisite defects that generate internal fields through localized tensile strain. Under an upward external field, this competitive landscape forces the formation of a stable, head-to-head domain wall within the 3-nanometer-thick BaTiO₃ barrier, preventing the system from reaching a homogeneous polarization state. Our findings demonstrate that ferroelectric reversibility is fundamentally constrained by a mutual stabilization of cation and anion defects, providing a framework for engineering electrode interfaces at the limit of unit-cell thickness.

PMID:
42748254
Bibliographic data and abstract were imported from PubMed on 17 Sep 2026.

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