This is a very exciting question and relatively easy to answer.
High Energy Magnets
Are permanent magnets. They come from the rare earth group. These magnets have a very high energy product of over 385 kJ/m³ or 48 MGOe and enable completely new technical solutions. These include reductions/minimisations of existing or completely new magnet systems or considerably higher magnetic energies with the same size compared to conventional magnet materials such as BaFe or AlNiCo.
Let's look at a simple comparison:
For the same energy content, a BaFe magnet must have a volume 6 x larger than/strong>. In order to generate a field of 100 mT (1000 Gauss) at a distance of 1 mm from the pole face, a barium ferrite magnet must have a volume >strong>. 25 x larger than a samarium-cobalt magnet. This example alone shows a positive development of the new magnet generation.
Also the energy product of the new neodymium-iron-boron magnets, which are already widely used today, is about 70% higher than the samarium-cobalt magnets mentioned in the example. The disadvantage is rather corrosion and oxidation. You have to pay attention to the application possibilities under humid conditions.
Below is a comparison of the energy products (W x H) max. of some magnetic materials:
Hard ferrite, sintered, anisotropic (SrFe) = 32 kJ/m3
AlNiCo = 40 kJ/m3
Samarium-Cobalt (SmCo) = 225 kJ/m3
Neodymium iron boron (NdFeB) = 360 kJ/m3