Emergent Ferromagnetism at LaFeO3/SrTiO3 Interface Arising from a Strain‐Induced Spin‐State Transition

Abstract Creating new interfacial magnetic states with desired functionalities is attractive for fundamental studies and spintronics applications. The emergence of interfacial magnetic phases demands the fabrication of pristine interfaces and the characterization and understanding of atomic structur...

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Main Authors: Menglin Zhu, Joseph Lanier, Sevim Polat Genlik, Jose G. Flores, Victor da Cruz Pinha Barbosa, Mohit Randeria, Patrick M. Woodward, Maryam Ghazisaeidi, Fengyuan Yang, Jinwoo Hwang
Format: Article
Language:English
Published: Wiley-VCH 2025-07-01
Series:Advanced Materials Interfaces
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Online Access:https://doi.org/10.1002/admi.202500169
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Summary:Abstract Creating new interfacial magnetic states with desired functionalities is attractive for fundamental studies and spintronics applications. The emergence of interfacial magnetic phases demands the fabrication of pristine interfaces and the characterization and understanding of atomic structure as well as electronic, magnetic, and orbital degrees of freedom at the interface. Here, a novel interfacial insulating ferromagnetic order in epitaxial films of LaFeO3 grown on SrTiO3 characterized by a combination of electron microscopy and spectroscopy, magnetometry, and density functional theory, is reported. The epitaxial strain drives a spin‐state disproportionation in the interfacial layer of LaFeO3, which leads to a checkerboard arrangement of low‐ and high‐spin Fe3+ ions inside smaller and larger FeO6 octahedra, respectively. Ferromagnetism at the interface arises from superexchange interactions between the low‐ and high‐spin Fe3+. Moving away from the interface the structure relaxes and the antiferromagnetic order seen in bulk LaFeO3 is restored. It demonstrates how strain‐induced spin‐state disproportionation at the interface creates a novel ferromagnetic superexchange interaction in magnetic insulators, offering a new pathway to engineer interfacial magnetism for spintronic applications.
ISSN:2196-7350