Why is diamagnetism, in contrast, almost independent of temperature?

Explanation

Diamagnetism occurs due to change in orbital magnetic moment of paired electrons on application of magnetising field. Electrons with orbital magnetic moment in the same direction as the applied field slow down, and those in opposite direction speed up. Thus induced dipole moment in a diamagnetic sample is always opposite to the magnetising field, irrespective of the internal motion of the atoms. Since, the internal motion is dependent on the temperature of the sample, so the induced dipole moment is almost independent of temperature.