Nano Magnetism-

Magnetism can be explained at the atomic level by the overlap of electron wave functions when their spin interactions are taken into consideration. The behaviour of a magnetic system gets more difficult to anticipate at the nanometer length scale.

When the size of a magnetic material is lowered, the number of domains within the material is reduced until only one domain remains. It is feasible to make strong permanent magnets using only single domains. However, if the sample's size is lowered below a specific point, it becomes superparamagnetic and loses its ferromagnetism.

The coercivity as a function of magnetic particle size is depicted in the diagram. The number of domains in a particle decreases as it shrinks. The magnetic particle becomes a single domain at a specific size – often in the range of 10-100nm – depending on the material. Particles smaller than 10 nm become superparamagnetic. Within the particle, the spin is continually changing.

To make a high-performance permanent magnet, the particle size should be set so that coercivity and remanence are both maximised.Magnetic nanoparticles have recently attracted a lot of attention due to their appealing features, which could lead to applications in catalysis, such as nanomaterial-based catalysts, biomedicine, and tissue-specific targeting.

Nanomagnetism is the area of research in physics, which deals with the magnetic properties of objects that have at least one dimension in the nanoscopic range. Nanomagnetism includes in its scope the study of properties and applications of the magnetism of isolated nanoparticles, nanodots, nanowires, thin films and multilayers, and also macroscopic samples that contain nanoscopic particles. Materials that contain particles, films, and other structures in the nanometric scale are often described as nanostructured materials. Objects with dimensions from 100 to 1,000 nm are usually described as mesoscopic; although our focus in the present work is on magnetic properties of objects of nanoscopic dimension, we will also consider the behavior of objects of mesoscopic size.