Types of Magnetism -magnetic material
At first Magnetic materials Material may be classified into one of five categories depending on its magnetisation characteristics.
- Diamagnetic materials
- Paramagnetic materials
- Antiferromagnetic materials
- Ferromagnetic materials
- Ferromagnetic materials
Also Diamagnetic, Paramagnetic and Antiferromagnetic material were non-magnetic material.
Also Ferromagnetic and Ferrimagnetic materials magnetic materials.
A material whose relative permeability is less than unity (µ < 1). Since µr = 1 + Xmr this can only happen when Xmr is negative. The intrinsic magnetization occurs in the opposite direction to the applied H. It will be repelled when placed near a magnet. Diamagnetic materials try to shield to applied field from the interior of the materials.
Example for Diamagnetic materials is Cu, Ag, Au and super conductor materials.
A material whose relative permeability is slightly greater than unity (µ > 1 ) and also independent of the magnetization force H. Therefore, a small positive susceptibility presents to external magnetic fields, but does not retain when the external field is removed. Most nonmagnetic materials fall into this category.
Example Paramagnetic materials Mg, Mo, Li, Ta
Antiferromagnetic Materials -magnetic materials
A material whose magnetic moments are lined up antiparallel to neighbors. Hence net intrinsic magnetization is zero (Bi = 0). i.e No hysteresis effect. However, this happens at sufficiently low temperature, but vanishes, at above a critical temperature called Neel temperature. Above the Neel temperature, the material become paramagnetic.
Example for Antiferromagnetic Materials is metals such as Cr, alloy
Br = Remannet Flux density
Hc =Coercive force
A material with relatively large µ, which also exhibits hysteresis and saturation (i.e µ is not constant, nonlinear B – H curve). Large positive susceptibility to an external magnetic field. Ferromagnetic materials have some unpaired electrons thus have a net magnetic moment. Pure ferromagnetic elements Iron, Ni, Co and alloys of them
Ferromagnetic materials in range of 100 < µ < 300000.
Ferrimagnetic Materials – magnetic materials
Same as ferromagnetism but occurs in ferrites which are materials with ferric oxide (Fe2O3) as a component. Saturatio0n flux density is lower than it for ferromagnetic, but ferrites have very high electrical resistivity. i. e useful for radiofrequency applications.
Also, we can divide Magnetic materials as soft and hard magnetic material.
Soft Magnetic Materials
- Easily magnetized easily demagnetized
- High µ
- Low core loss
- Thus, used as magnetic core material
- Examples – Iron, iron-silicon alloy, Ni- Fe alloy
Soft Ferro magnetic Materials
Hard Magnetic Material
- Difficult to magnetize and difficult to demagnetize
- High BH product
- Used in permanent magnets, speaker, microphones etc.
Also Examples – Alloys of Fe, Co and Al
Hard Ferromagnetic Materials