The use of hard magnetic material NdFeB has offered quite significant performance benefits, which has enabled the development of highly efficient traction motors not possible with other technologies .
The use of hard magnetic material NdFeB offers quite significant benefits, which has enabled the development of highly efficient traction motors not possible with other technologies.
It is a familiar hard magnetic material
possessing high saturation magnetization and coercivity than zinc and nickel ferrites.
Being a hard magnetic material
, Barium hexaferrite has been a subject of continuous interest for several decades due to its applicability in electronic components, magnetic memories and recording media.
 and Kneller and Hawig  proposed the exchange spring magnet, based on an interfacial exchange coupling of two nanostructured phases combining a hard magnetic material
in order to provide large [H.sub.C] and a soft magnetic material to provide high [M.sub.S], as a way to create a next generation high performance permanent magnet and magnetic recording media.
The coercivity is mostly related to whether the magnetic material is a soft or a hard magnetic material
, i.e., the composition of the particles, and secondly to the size of the particles if one refers to ferromagnetic nanoparticles with sizes close to their critical domain size.
Hard magnetic materials
retain their magnetism even in the absence of an applied magnetic field.
Figure 5 shows the B-H fundamental magnetizing curve of magnetic materials, including hard magnetic materials
and soft magnetic materials.
Recent advances in this field include the magnetoresistance effect, diluted magnetic semiconductors, Hall effect, field-free magnetization switching, improved hard magnetic materials
, and the exploration of low-dimensional materials with controlled spin states.
In dentistry, so called hard magnetic materials
, which generate static or constant fields, are used.
These magnetic properties of the Sm-Fe-N/Co-B composite powder are very attractive for hard magnetic materials
. Compositional modification and optimization of the processing conditions can be expected to lead to further improvement of the magnetic properties of Sm-Fe-N/Co-B composite powder prepared by chemical reduction.
Numerical micromagnetic modeling based on the discretization by finite elements has widely been used to describe the magnetization reversal in nucleation and domain wall pinning controlled hard magnetic materials