Ferromagnetic Substances and Its Properties
Description:
The atoms of these materials like paramagnetic material have permanent magnetic dipole moments. The similar natures of dipoles are grouped in a small region called domain. These domains have a net magnetic moment in a particular direction. In the material, there are a large number of domains having magnetic moments in different directions making the net magnetic moment of the entire material zero. When the external magnetic field is applied to such ferromagnetic materials, then either the domains are oriented in such a way as to align with the direction of the field, or the size of the favorable domain increases. Generally, in the strong applied field the domains are aligned and in the weak field the size of the favorable domain increases. In both cases, the material is strongly magnetized in the direction of the applied external magnetic field.
Properties of Ferromagnetic Substances:
The properties of ferromagnetic substances are similar to the properties of diamagnetic substances but the difference is that diamagnetic substances are weakly magneties and ferromagnetic substances strongly magenties in the presence of magnetic field.
Properties of Ferromagnetism:
1.) If these materials are placed in an external magnetic field, they are strongly magnetized in the direction of the applied external magnetic field.
2.) Due to unpaired electrons, the atoms of ferromagnetic materials have a net magnetic dipole moment.
3.) Ferromagnetism arises due to the formation of domains.
4.) Magnetic susceptibility of these materials is high and positive and also inversely proportional to the absolute temperature:
$\chi=\frac{C}{T-T_{c}}$
where $T_{c}$ is Curie temperature.
5.) Relative permeability of these materials is much greater than 1.
6.) Magnetic moment is high but along the direction of the applied magnetic field.
7.) $Fe$, $Ni$, $Co$, etc. are examples of paramagnetic materials.
