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<p>Magnetic nanoparticles fabrication for various applications requires finding a way to control their morphology and size in a wide range. The technique of pulsed laser ablation in liquid looks promising to reach this aim. For further improvement in this direction, we propose using thin magnetic films as ablation targets. This paper demonstrates the possibility of synthesizing magnetic nanoparticles by pulsed laser ablation of cobalt nanofilms with 5–500&#xa0;nm thickness in water. The presence of unoxidized Co within the nanoparticles imparts them magnetic properties at room temperature. The morphology, mean size and size dispersion of the nanoparticles depend on the thickness of the ablated targets. When the nanofilms thickness exceeds 35&#xa0;nm (the skin layer depth), laser ablation results in the formation of the almost spherical particles with less than 100&#xa0;nm mean size and 40% relative standard deviation in size. In the case of laser ablation of nanofilms less than 35&#xa0;nm thick, one can observe both spherical and flocculent structures up to 1&#xa0;μm in size, but with a smaller size dispersion. This difference can be explained by the features of light absorption and laser-induced heating over the film depth: incident light is absorbed predominantly within the skin layer regardless of the film thickness, while thermal diffusion allows the heat to propagate deeper in thicker films. These features are also manifested in dependencies of the laser ablation crater diameter and the ablation threshold on the film thickness.</p>

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Features of magnetic nanoparticles formation under pulsed laser ablation of Co films with thicknesses of 5–500 nm in water

  • 期刊论文

  • 发表日期：

    2025年10月25日

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  • V. Yu. Nesterov,
  • I. O. Dzhun,
  • D. V. Shuleiko,
  • Ya. S. Mineev,
  • D. E. Presnov,
  • A. V. Nazarov,
  • N. G. Chechenin,
  • S. V. Zabotnov

摘要

Magnetic nanoparticles fabrication for various applications requires finding a way to control their morphology and size in a wide range. The technique of pulsed laser ablation in liquid looks promising to reach this aim. For further improvement in this direction, we propose using thin magnetic films as ablation targets. This paper demonstrates the possibility of synthesizing magnetic nanoparticles by pulsed laser ablation of cobalt nanofilms with 5–500 nm thickness in water. The presence of unoxidized Co within the nanoparticles imparts them magnetic properties at room temperature. The morphology, mean size and size dispersion of the nanoparticles depend on the thickness of the ablated targets. When the nanofilms thickness exceeds 35 nm (the skin layer depth), laser ablation results in the formation of the almost spherical particles with less than 100 nm mean size and 40% relative standard deviation in size. In the case of laser ablation of nanofilms less than 35 nm thick, one can observe both spherical and flocculent structures up to 1 μm in size, but with a smaller size dispersion. This difference can be explained by the features of light absorption and laser-induced heating over the film depth: incident light is absorbed predominantly within the skin layer regardless of the film thickness, while thermal diffusion allows the heat to propagate deeper in thicker films. These features are also manifested in dependencies of the laser ablation crater diameter and the ablation threshold on the film thickness.