Related Experiment Video
Updated: Mar 29, 2026

Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains
Published on: July 20, 2022
Hydrophilic Magnetochromatic Nanoparticles with Controllable Sizes and Super-high Magnetization for Visualization of
Lin Zhuang1, Yongxin Zhao1, Huixiang Zhong2
1School of Physics and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510006, China.
Abstract:
Hydrophilic Fe3O4 nanoparticles with controllable size and shape have been fabricated using a facile solvothermal approach followed by surface modification with polyacrylic acid (PAA). The nanoparticles form one-dimension photonic crystal structure under external magnetic field ranging from 29.6 to 459 G. The reflection peaks of formed photonic crystals cover the entire visible spectrum, which indicates a good magnetochromatic property and prospect of wide applications. The size and shape of Fe3O4 nanoparticles are controlled by changing the ratio between ethylene glycol and diethylene glycol. In the process of surface modification, PAA synthesized by free radical polymerization was chemisorbed onto the surface of Fe3O4 particles with the aid of Fe(3+) cations, which renders the particles well dispersed in aqueous solution with high thermo-stability. The Fe3O4 particles exhibit ferrimagnetism with a high saturation magnetization value of 88.0 emu/g. Both the high magnetization and the wide reflection spectrum under magnetic field make the magnetochromatic nanoparticles a promising material for visualization of the distribution of magnetic field intensity on microfluidic chips.
Related Concept Videos
Ferromagnetism
Paramagnetism
Diamagnetism
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
Magnetic Susceptibility and Permeability
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
Other Unique Bacteria
Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...

