Thermal annealing reduction of ALD hematite into magnetite nanotubes: Optimized magneto-structural properties for multifunctional applications
The fabrication of 3D nanomagnetic materials with controlled geometry, composition, microstructure and magnetic properties is crucial for developing multifunctional devices with nanotechnological applications. Here we report on the synthesis of high-quality magnetite nanotubes using the thermal redu...
| Autores: | , , , , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:dnet:idus________::f5d952352dde4e596066c0ed4255c6de |
| Acceso en línea: | https://hdl.handle.net/11441/186917 https://doi.org/10.1016/j.surfcoat.2026.133557 |
| Access Level: | acceso abierto |
| Palabra clave: | Magnetic nanotubes Magnetite ALD Nanoporous alumina templates Spintronics |
| Sumario: | The fabrication of 3D nanomagnetic materials with controlled geometry, composition, microstructure and magnetic properties is crucial for developing multifunctional devices with nanotechnological applications. Here we report on the synthesis of high-quality magnetite nanotubes using the thermal reduction treatment of hematite precursor deposited by atomic layer deposition technique within the hexagonally self-ordered nanopores of an anodic alumina membrane, employed as patterned template. The applied synthesis procedure adequately controls both the geometric parameters of the alumina template (pore length and diameter, interpore distance and porosity) and the single nanotube (wall thickness and inner diameter). Microstructural and magnetic characterizations confirm the complete phase conversion from weak magnetic hematite to ferrimagnetic magnetite, clearly evidenced by the sharp Verwey metal-insulator transition observed at ~120 K in the temperature-dependent magnetization curves. The magnetite/hematite ratio estimated using both M¨ ossbauer and Raman spectroscopies yield consistent values of approximately 70% magnetite and 30% hematite. Assessing the coercive field and reduced remanence dependences on nanotube wall thickness reveals the influence of magnetic shape anisotropy, evidenced by coercive field and reduced remanence values being consistently higher when the field is applied parallel to the nanotube longitudinal axis, and showing a critical dependence on nanotube wall thickness reaching a maximum value at 10 nm before stabilizing for larger values. The micromagnetic simulations performed by Mumax3 software reproduce also this magnetic behavior, unveiling the formation of a C-state magnetic domain during the magnetization reversal of a single magnetite nanotube with 2 nm in wall thickness. Therefore, these results demonstrate the effectiveness of the applied methodology to obtain magnetite nanostructures with optimized geometrical and magneto-structural properties, positioning them as promising candidates for applications in spintronics and magnetic sensing |
|---|