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Abstract Intrinsic exchange bias is known as the unidirectional exchange anisotropy that emerges in a nominally single-component ferro-(ferri-)magnetic system. In this work, with magnetic and structural characterizations, we demonstrate that intrinsic exchange bias is a general phenomenon in (Ni, Co, Fe)-based spinel oxide films deposited on -Al2O3(0001) substrates, due to the emergence of a rock-salt interfacial layer consisting of antiferromagnetic CoO from interfacial reconstruction. We show that in NixCoyFe3−x−yO4(111)/ -Al2O3(0001) films, intrinsic exchange bias and interfacial reconstruction have consistent dependences on Co concentrationy, while the Ni and Fe concentration appears to be less important. This work establishes a family of intrinsic exchange bias materials with great tunability by stoichiometry and highlights the strategy of interface engineering in controlling material functionalities.
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This content will become publicly available on December 20, 2025
Interfacial charge transfer and its impact on transport properties of LaNiO 3 /LaFeO 3 superlattices
Charge transfer or redistribution at oxide heterointerfaces is a critical phenomenon, often leading to remarkable properties such as two-dimensional electron gas and interfacial ferromagnetism. Despite studies on LaNiO3/LaFeO3superlattices and heterostructures, the direction and magnitude of the charge transfer remain debated, with some suggesting no charge transfer due to the high stability of Fe3+(3d5). Here, we synthesized a series of epitaxial LaNiO3/LaFeO3superlattices and demonstrated partial (up to ~0.5 e−/interface unit cell) charge transfer from Fe to Ni near the interface, supported by density functional theory simulations and spectroscopic evidence of changes in Ni and Fe oxidation states. The electron transfer from LaFeO3to LaNiO3and the subsequent rearrangement of the Fe 3d band create an unexpected metallic ground state within the LaFeO3layer, strongly influencing the in-plane transport properties across the superlattice. Moreover, we establish a direct correlation between interfacial charge transfer and in-plane electrical transport properties, providing insights for designing functional oxide heterostructures with emerging properties.
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- Award ID(s):
- 2011401
- PAR ID:
- 10589985
- Publisher / Repository:
- Sci. Adv.
- Date Published:
- Journal Name:
- Science Advances
- Volume:
- 10
- Issue:
- 51
- ISSN:
- 2375-2548
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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