Nanocomposites that can respond to an external stimulus are of increased interest due to the fact that, because of the large amount of interaction between the phase interfaces, the stimulus response can have a larger effect on the composite as a whole.  The external stimulus can take many forms, such as a magnetic, electrical, or mechanical field.  Specifically, magnetic nanocomposites are useful for use in these applications due to the nature of magnetic material's ability to respond both to electrical and magnetic stimuli.  The penetration depth of a magnetic field is also high, leading to an increased area that the nanocomposite is affected by and therefore an increased response.  In order to respond to a magnetic field, a matrix can be easily loaded with nanoparticles or nanorods The different morphologies for magnetic nanocomposite materials are vast, including matrix dispersed nanoparticles, core-shell nanoparticles,
colloidal crystals, macroscale spheres, or Janus-type nanostructures.
Magnetic nanocomposites can be utilized in a vast number of applications, including catalytic, medical, and technical.  For example, palladium is a common transition metal used in catalysis reactions.  Magnetic nanoparticle-supported palladium complexes can be used in catalysis to increase the efficiency of the palladium in the reaction.
Magnetic nanocomposites can also be utilized in the medical field, with magnetic nanorods embedded in a polymer matrix can aid in more precise drug delivery and release.  Finally, magnetic nanocomposites can be used in high frequency/high-temperature applications.  For example, multi-layer structures can be fabricated for use in electronic applications.  An electrodeposited Fe/Fe oxide multi-layered sample can be an example of this application of magnetic nanocomposites.
In applications such as power micro-inductors where high magnetic permeability is desired at high operating frequencies. The traditional micro-fabricated magnetic core materials see both decrease in permeability and high losses at high operating frequency. In this case, magnetic nano composites have great potential for improving the efficiency of power electronic devices by providing relatively high permeability and low losses. For example, As Iron oxide nano particles embedded in Ni matrix enables us to mitigate those losses at high frequency. The high resistive iron oxide nanoparticles helps to reduce the eddy current losses where as the Ni metal helps in attaining high permeability. DC magnetic properties such as Saturation magnetization lies between each of its constituent parts indicating that the physical properties of the materials can be altered by creating these nanocomposites.