Proximity effects, exchange bias and magnetic relaxation in γ-Fe2O3 nanoparticles
Carbon-encapsulated γ-Fe2O3 nanoparticles (NPs) with emerging proximity effects were synthesized using a single-step solid-state pyrolysis at 750 °C. The morphology and size distribution of the NPs were investigated using high-resolution transmission and scanning electron microscopies revealing that...
| Autores: | , , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:dnet:digitalcsic_::141ce8a8c143ce730f98265fa4b90034 |
| Acceso en línea: | http://hdl.handle.net/10261/426336 https://api.elsevier.com/content/abstract/scopus_id/105018119493 |
| Access Level: | acceso abierto |
| Palabra clave: | http://metadata.un.org/sdg/9 http://metadata.un.org/sdg/7 Ensure access to affordable, reliable, sustainable and modern energy for all Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation |
| Sumario: | Carbon-encapsulated γ-Fe2O3 nanoparticles (NPs) with emerging proximity effects were synthesized using a single-step solid-state pyrolysis at 750 °C. The morphology and size distribution of the NPs were investigated using high-resolution transmission and scanning electron microscopies revealing that the γ-Fe2O3 NPs, with an average diameter of 9 nm, are embedded in the amorphous porous carbon matrix. In addition, other trace phases (Fe3C and metallic-Fe) were also detected through X-ray absorption spectroscopy and Mössbauer spectrometry. Moreover, the dynamics of the system was explored by means of AC susceptibility, magnetic memory and relaxation measurements, together with low-temperature exchange bias, suggesting the emergence of a spin-glass-like state that remains robust under magnetic cooling fields up to 140 kOe. These findings point to a strong exchange coupling between the spins in the ordered core and those on the disordered surface of the maghemite nanoparticles. Furthermore, the identification of robust spin-glass behaviour under high cooling fields and the demonstration of coexisting blocked and superparamagnetic phases at room temperature provide valuable insights for applications in magnetic data storage and spintronics. |
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