Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond curie temperature, then it will show

Options

A. Paramagnetism
B. anti-ferromagnetism
C. no magnetic property
D. diamagnetism

Answer

A

Explanation

Nickel exhibits ferromagnetism because of a quantum physical effcet called exchange coupling in which the electron spins of one atom interact with those of neighbouring atoms. The result is alignment of the magnetic dipole moment of the atoms, inspite of the randomizing tendency of atomic collisions. This persistent alignment is what given ferromagnetic meterials their permanent mangetism.
If the temperature of a ferromagnetic is rasied above a certain critical value, called the Curie temperature, the exchange coupling ceases to be effective. Most such materials then become simply paramagnetic, that is, the dipoles still tend align with an external field but much more weakly, and thermal agitation can now more easily disrupt the alignment.