Classification of magnetic materials: 1)Paramagnetic materials 2)Diamagnetic materials 3)Ferromagnetic materials
a. Paramagnetic materials: The relative permeability of such materials is very less but positive (slightly greater than 1) so these materials cannot be magnetized and not suitable to carry the flux from one place to the other. In their case, the individual atomic di-poles are oriented in a random fashion. Following are the paramagnetic materials: magnesium, molybdenum, lithium, Aluminium, Titanium, Platinum.
b. Diamagnetic materials: These materials have relative permeability slightly less than one. Such materials are magnetized opposite to the direction of the external field and due to this they are pushed out of regions of the highest field intensity. So diamagnetic materials are not useful in magnetic applications. Most elements in periodic table, including Copper, Silver and Gold fall in this category.
c. Ferromagnetic materials: Relative permeability of ferromagnetic material is very large. These materials are very easily magnetized and used as conductors of magnetic flux from one place to other. These materials are characterized by the presence of parallel alignment of permanent magnetic dipole moments in a single direction. In the ferromagnetic materials the magnetization arises spontaneously i.e. in the absence of external magnetic field. Following are the ferromagnetic materials: Iron, Cobalt, Nickel.