Properties of Material

Properties of diamagnetic materials

(i)    For diamagnetic substances μr slightly less than unity.
(ii)    The susceptibility (χm) of a diamagnetic material has a low negative value. It is independent of temperature.
(iii)    In an external magnetic field, they get magnetized in a direction opposite to the field and so they have a tendency to move away from the field.
(iv)    If suspended freely, they set themselves | to the field.

Sb, Bi, Zn, Ag, Au,  Pb etc., are examples of diamagnetic materials.

Properties of paramagnetic materials

(i)    These substances have μr > 1 and χm +ve.
The susceptibility decreases with rise in temperature.
(ii)    In an external magnetic field, these substances get magnetized in the direction of the field. Hence they move from weaker to stronger part of the external field.
(iii)    If suspended freely, they set themselves || to the field.

Platinum, aluminum, chromium, manganese, copper sulphate, liquid oxygen and solution of salts of iron and nickel are examples of paramagnetic substances.

Properties of ferromagnetic materials

(i)    They values of μr and χm of these materials are very large.
(ii)    They get strongly magnetized in the direction of the external field and so they are strongly attracted by magnets.
(iii)    They set themselves parallel to the external field if suspended freely.
(iv)    These materials exhibit the phenomenon of hysteresis.
(v)    As temperature increases, the value of χm decreases. Above a certain temperature, known as Curie temperature, ferromagnetic become paramagnetic.

Iron, nickel and cobalt are some examples of Ferro-magnetic substances.
There exist two other types of magnetism, closely related to ferromagnetism. These are anti ferromagnetism and ferrimagnetism.