paramagnetit

Paramagnetism is a form of magnetism that occurs only in the presence of an external magnetic field. Materials exhibiting paramagnetism are weakly attracted to this applied field. This attraction arises from the presence of unpaired electrons within the atoms or molecules of the material. These unpaired electrons possess a magnetic dipole moment, which, in the absence of an external field, are randomly oriented. When an external magnetic field is applied, these dipoles tend to align with the field, creating a net magnetic moment in the direction of the applied field.

The key characteristic of paramagnetism is that this alignment is temporary. When the external magnetic field is removed, the thermal motion of the atoms or molecules disrupts the alignment of the magnetic dipoles, and the material loses its net magnetization. Paramagnetic materials do not retain any magnetism in the absence of an external field. Their magnetic susceptibility is positive but small, meaning the induced magnetization is much weaker than the applied field. Examples of common paramagnetic materials include aluminum, oxygen, and platinum. This property makes them useful in various applications, such as in magnetic resonance imaging (MRI) contrast agents and certain types of sensors.