Question

Define Curie temperature in magnetism.

Answer 1

Hint: A ferromagnetic material has small magnetic domains in it. In a single domain, the magnetic axis of all the atoms are in the same direction. The minimum temperature at which the domain structure of a ferromagnetic material gets completely destroyed is called the Curie temperature. Above the Curie temperature, a ferromagnetic substance is converted into a paramagnetic substance.

Complete step by step solution:
It has been observed that with increase in heat, the temperature of ferromagnetic substances increases and hence its magnetism decreases with temperature. At a particular maximum temperature, these substances lose their magnetism completely. The reason behind this is, at this maximum temperature its domain structure completely vanishes. The maximum temperature at which the domain structure destroys completely and ferromagnetic substance loses its magnetism property is called Curie temperature.
With increase in temperature, atoms in the substance get thermal energy and vibrations of the atoms in the given ferromagnetic substance are increased and as a result, the interatomic coupling between atoms becomes weak. At a higher temperature, the exchange coupling between the atomic magnets in each domain breaks completely and all the atomic dipoles get randomly oriented, destroying the structure.
About the Curie temperature, ferromagnetic substance is converted into paramagnetic substance. The Curie temperature is different for the different ferromagnetic material.

Note: If ferromagnetic substances cooled below curie temperature then it will again gain ferromagnetism. The net magnetic dipole moment per unit volume is called the magnetization of the sample. Magnetic intensity is a quantity used in describing magnetic phenomena in terms of their magnetic fields. The strength of the magnetic field at a point can be given in terms of a vector quantity called magnetic intensity.