Introduction:

• Magnetic property is one of the most important properties, which helps to classify different types of magnetic materials. For instance, magnetic materials may be classified by their response to externally applied magnetic fields as diamagnetism, paramagnetism, ferromagnetism, antiferromagnetism and ferrimagnetism.

• Although the phenomenon of magnetism was known to many ancient civilizations, the first recorded description is from the Greek Thales of Miletus, who shared the attraction of loadstone to iron.

• Magnetism arises from charge in motion, whether at the microscopic level through the motion of electrons in atomic orbitals or at macroscopic level by passing current through a wire. The magnetization of a material is expressed in terms of density of net magnetic dipole moments, i.e., M=μ_total /V. The total magnetic field B in the materials is therefore given as B=B₀ + μ₀ M where μ₀ is the magnetic permeability of space and B₀ is the externally applied magnetic field.

• If one calculates the magnetic field inside materials using Ampere's law or the Biot-Savart law, then the term μ₀ is replaced by μ with the definition that μ=μ₀μ_r, where μ_r is called relative permeability.

• If any materials do not respond to the applied field by showing any magnetization, then the value of relative permeability is considered to be 1. In such case, another magnetic parameter called magnetic susceptibility is used to specify how much the relative permeability differs from 1→χ+1= μ.