The magnetic susceptibility is negative for

For paramagnetic and diamagnetic materials the intensity of magnetization I of a material is directly proportional to the magnetic intensity H

..(i)

This proportionality constant is known as susceptibility of a material.

Now in a diamagnetic material the individual atoms of the material do not have a net magnetic dipole moment. When such a substance is placed in a magnetic field, dipole moments are induced by the applied field. From lenz’s law the magnetic fields due to induced magnetic moment opposes the original field

The magnetization () and magnetic intensity () are therefore in opposite direction and of a diamagnetic material is therefore negative.

Therefore, susceptibility of a material is negative only for diamagnetic materials