Question

What is Curie temperature? How magnetic susceptibility of dia, para and ferro magnetic substances depend on temperature? Explain and write essential law for it.

Answer 1

Hint: In order to solve the above question first we will find what the meaning Curie temperature is then we will check what magnetic susceptibility is and how it varies in accordance with the paramagnetic substances and ferro magnetic substances.

Complete step-by-step solution:
In the question above we are first asked about what is Curie temperature? Let us first discuss that only:
Curie temperature is the temperature at which the transition from ferromagnetic to paramagnetic takes place. In simple language it can be defined as the temperature at which the magnetic material completely loses its properties. It is denoted by the symbol\[{{T}_{c}}\].
Now, let us try and find how magnetic susceptibility of di, para and ferro magnetism depends on Curie temperature?
Case 1: For paramagnetic substances;
We know that the magnetic susceptibility of a paramagnetic material varies inversely as the absolute temperature that means when temperature increases the magnetic susceptibility decreases and when the temperature decreases the magnetic susceptibility increases.
\[\begin{align}
  & {{X}_{m}}\prec \dfrac{1}{T} \\
 & {{X}_{m}}=\dfrac{C}{T} \\
\end{align}\]
Where \[{{X}_{m}}\]is the magnetic susceptibility of the paramagnetic substance; T is absolute temperature and C is the constant which is called Curie’s constant and the above equation is known as Curie’s law.
Case 2: For ferro magnetic substances;
The susceptibility of ferromagnetic substances decreases with temperature in accordance with Curie-Wiess law:
\[{{X}_{m}}=\dfrac{C}{T-{{T}_{c}}}\]
Where \[{{X}_{m}}\]is magnetic susceptibility, C is the Curie constant and \[{{T}_{c}}\]is the Curie temperature for magnetic substances
The Curie’s law states that when we have a paramagnetic material, the material’s magnetization will be directly proportional to an applied magnetic field. But the case is not the same when the material is heated. When it is heated, the relation is reversed, that is the magnetization becomes inversely proportional to temperature.
The susceptibility above the Curie temperature i.e., in the paramagnetic phase is described by
\[X=\dfrac{C}{T-{{T}_{c}}}\];\[(T>{{T}_{c}})\]

Note: In the question given here we got to know that magnetic susceptibility of any paramagnetic and ferromagnetic substances depends on Curie’s temperature. And Curie’s temperature is the temperature when a magnetic substance completely loses its magnetic properties.