XSD/MIC Virtual Special Scientific Presentation Scott Smith
Speaker: Scott Smith-Postdoctoral AppointeeTitle: “Imaging Oxygen Dependent Phase Transitions in La1-xSrxCoO3
Heterostructures & in-Operando Devices”
Date: Friday, January 16, 2026
Location: TEAMS Join the meeting now
Time: 1:00 p.m. CDT
Host: Junjing Deng
Abstract:
Manipulating oxygen stoichiometry in complex oxides like La1-xSrxCoO3(LSCO) via a reactive metal layer offers a pathway to tune emergent properties by driving the topotactic Perovskite (P) to
Brownmillerite (BM) transition. My presentation will focus on my efforts to use synchrotron x-ray nanodiffraction imaging to visualize the subsequent P-to-BM phase separation, filamentation, and associated nanoscale strain in LSCO heterostructures and devices. First, in static LSCO/Al heterostructures, we find BM formation proceeds via dominant filamentary growth. Fascinatingly, filament elongation at the advancing front (i.e. filament tip) appears to be a highly dominant growth mechanism in this system, apparently out-competing further nucleation, branching, and even broadening of existing BM filaments. Nanodiffraction reveals significant local strain gradients at P-BM boundaries, suggesting asymmetric local strain strongly correlates with and likely mediates the transformation pathway. Second, I address the challenge of directly electrically gating complex oxides, by using reactive metal interdigitated electrodes (e.g., Gd) LSCO to promote the P-to-BM transition. With in-
operando nanodiffraction I demonstrate controlled, polarity-dependent, voltage-driven P-to-BM conversion. This architecture provides a novel and flexible platform for dynamic strain engineering, yielding large (>0.98%), reversible, polarity-dependent strains that also retaining access to the inter-electrode region. This opens avenues for probing strain-coupled phenomena and designing dynamically controlled devices with application in energy, catalysis, and computing sectors. Overall, this work provides key nanoscale insights into chemically and electrically driven oxygen-mediated P-to-BM phase transitions, highlighting the critical role of local strain and demonstrating
a novel approach for active device control and dynamic strain engineering.
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