Help in superparamagnetism devices

[sniffer]

does anyone know some useful devices or applications which make use of superparamagnetism phenomena?

or a website which discuss these devices.

thanks.

 

[Gokul43201]

As far as devices go, from my half-baked knowledge, superparamagnetism is a bad thing. At some spin density, the exchange interaction has a magnitude that makes the material go paramagnetic (in little portions) at room temperature, due to thermal fluctuations. So, I believe, you have an essentially ferromagnetic material with little paramagnetic domains dispersed in it.

As for other applications, I've heard of some in the medical imaging industry, but more commonly, dispersions of some transition metal oxides are used in heterogeneous catalysis - for instance in the hydrogenation of vegetable oils. I'm not sure what the role of the magnetic nature of the material is though.

 

[charng]

Superparamagnetism is a phenomenon that occurs in materials with very small magnetic particles, typically less than 10 nanometers in size. These particles exhibit random fluctuations in their magnetic moments, leading to a lack of long-range magnetic order. This property has been utilized in various devices and applications in recent years.

One example of a device that utilizes superparamagnetism is the magnetic hard disk drive. The storage media in these drives contains magnetic particles that are small enough to exhibit superparamagnetism. This allows for higher storage densities as the particles can be packed more closely together.

Another application of superparamagnetism is in drug delivery systems. Magnetic nanoparticles can be coated with a biocompatible material and used to deliver drugs to specific locations in the body using an external magnetic field.

In terms of websites, I would recommend checking out the National Nanotechnology Initiative's website, which has a section on superparamagnetism and its applications. Additionally, the American Physical Society's website also has a section on magnetism and magnetic materials, which includes information on superparamagnetism and its applications.