Internal structural relaxation decoupled from lattice parameters in epitaxial films (Posted: Oct. 11th, 2026)

Abstract

The octahedral tilt relaxation has remained largely unexplored in epitaxial perovskite oxide films. We demonstrate that electrochemical operation induces internal structural relaxation in epitaxial La0.7Sr0.3CoO3 films while in-plane lattice parameters remain locked to the substrate. A sufficient number of film's Bragg reflections were measured by synchrotron x-ray diffraction, revealing that prolonged electrochemical treatment drives the octahedral tilt mode from the as-grown strained configuration toward the bulk structure without conventional lattice parameter changes. A reduction in energy barriers between structural configurations was triggered by ionic oxygen migration during electrochemical reactions. Our findings highlight the importance of monitoring internal atomic arrangements under operating conditions and offer a versatile strategy for designing strain-engineered functional materials by controlling internal structure in epitaxial oxides.

Our study was online published in Physical Review Materials on October 5th, 2026.

internal structural relaxation
Schematic of the free energy landscape. The structures of PR (a−b0c−) and P07-1h (a−a−c−) represent different local minima separated by a potential barrier. Electrochemically induced oxygen movement (cyan arrows) lowers this barrier, enabling tilt-mode transition between the two configurations. Copyright: American Physical Society

Publication details

Title: Octahedral tilt relaxation decoupled from lattice parameters in epitaxial perovskite oxide films

Authors: Xuhui Xu*, Yuta Ishii, Hidekazu Shimotani, Yuta Inoue, Yuto Miyahara, Kohei Miyazaki, Masao Nakamura, Daisuke Okuyama, Hajime Sagayama, Kakeru Ninomiya, Maiko Nishibori, and Yusuke Wakabayashi†
*Corresponding author: Xuhui Xu
†Corresponding author: Yusuke Wakabayashi

Journal: Physical Review Materials

DOI: 10.1103/72nx-sczv

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