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<p>Nickel ferrite (NiFe₂O₄) nanocrystals (10–25&#xa0;nm), synthesized via a low-temperature hydrothermal method, were investigated for their structural and magnetic properties as functions of standing time and Ni²⁺/Fe³⁺ concentrations. The Ni₀.₆₀Fe₂.₄₀O₄ composition exhibited enhanced saturation magnetization and reduced magnetic anisotropy, confirmed by temperature- and field-dependent magnetization measurements and electron magnetic resonance. To elucidate dynamic magnetization processes, alternating magnetic force microscopy (A-MFM) with a superparamagnetic tip was employed, enabling simultaneous quantitative and qualitative analysis of reversible and irreversible magnetization under alternating current (AC) magnetic fields. Comparative imaging revealed magnetic field profiles at ± 250 Oe (DC), 250 Oe (AC peak-to-peak) without DC bias, and AC fields (20–300 Oe) at a constant 60 Oe DC field. Increasing AC field intensity reduced the phase image signal, indicating magnetization saturation in the positive field direction. These insights into the magnetic dynamics of nickel ferrite nanoparticles highlight their potential for optimized applications in magnetic sensors, medical diagnostics, and data storage.</p>

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Decoding nickel ferrite magnetism at the nanoscale with AC-Modulated magnetic force microscopy

  • 期刊论文

  • 发表日期：

    2025年7月11日

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  • K. Jayanthi,
  • M. Rakshita,
  • Pawan Kumar,
  • P. V. N. M. Kaushik,
  • Sunkara V. Manorama,
  • D. Haranath

摘要

Nickel ferrite (NiFe₂O₄) nanocrystals (10–25 nm), synthesized via a low-temperature hydrothermal method, were investigated for their structural and magnetic properties as functions of standing time and Ni²⁺/Fe³⁺ concentrations. The Ni₀.₆₀Fe₂.₄₀O₄ composition exhibited enhanced saturation magnetization and reduced magnetic anisotropy, confirmed by temperature- and field-dependent magnetization measurements and electron magnetic resonance. To elucidate dynamic magnetization processes, alternating magnetic force microscopy (A-MFM) with a superparamagnetic tip was employed, enabling simultaneous quantitative and qualitative analysis of reversible and irreversible magnetization under alternating current (AC) magnetic fields. Comparative imaging revealed magnetic field profiles at ± 250 Oe (DC), 250 Oe (AC peak-to-peak) without DC bias, and AC fields (20–300 Oe) at a constant 60 Oe DC field. Increasing AC field intensity reduced the phase image signal, indicating magnetization saturation in the positive field direction. These insights into the magnetic dynamics of nickel ferrite nanoparticles highlight their potential for optimized applications in magnetic sensors, medical diagnostics, and data storage.