Related Experiment Video
Updated: Jan 10, 2026
07:42
Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains
Published on: July 20, 2022
3.2K
Turning Superparamagnetic Nanoparticles Into Ferromagnetic at Room Temperature via Molecular Functionalization for
Neha Singh1, Anurag Pritam1, Vikram Singh2
1Department of Chemistry, Indian Institute of Technology, Kanpur, Uttar Pradesh, 208016, India.
Angewandte Chemie (International Ed. in English)
|November 25, 2025
Summary
Covalent functionalization of cobalt ferrite nanoparticles with aryl compounds creates robust interfaces. This modification transforms superparamagnetic nanoparticles into room-temperature ferromagnets with enhanced magnetic properties for advanced applications.
Area of Science:
- Materials Science
- Nanotechnology
- Magnetism
Background:
- Molecular functionalization of magnetic oxide nanoparticles is key for interfacial engineering.
- Non-covalent methods lack robust interfaces for practical applications.
Purpose of the Study:
- To achieve covalent surface modification of cobalt ferrite (CoFe2O4) nanoparticles (NPs).
- To enhance interfacial electronic coupling and tune magnetic properties.
Main Methods:
- Utilized aryl diazonium salts for covalent functionalization of CoFe2O4 NPs.
- Established carbon-metal (C-M) covalent bonds at the nanoparticle-molecule interface.
- Employed zero-field-cooled/field-cooled magnetization and thermoremanent magnetization measurements.
Main Results:
- Achieved robust interfaces with chemical stability and tunable magnetic properties.
- Transformed superparamagnetic CoFe2O4 NPs into room-temperature ferromagnets.
- Observed significant increases in coercivity, remanent magnetization, saturation magnetization, and blocking temperatures (Tb from 245.9 K to 336.8 K).
Conclusions:
- Covalent aryl functionalization provides a versatile strategy to engineer magnetic nanoparticle properties.
- Enhanced surface spin ordering and anisotropy contribute to ferromagnetism.
- Potential applications in spintronics, spin-based memory, and spin logic.
Related Concept Videos
01:31Ferromagnetism
2.9K
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
2.9K
01:30Paramagnetism
3.0K
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
3.0K