Paramagnetic materials are substances that are attracted to an external magnetic field. This property arises due to the presence of unpaired electrons in the material's atoms or molecules, which creates a net magnetic moment. When exposed to a magnetic field, these unpaired electrons align, although this alignment is usually weak and disappears once the external magnetic field is removed.
Paramagnetic materials differ from diamagnetic materials, which are repelled by magnetic fields, and from ferromagnetic materials, which have a strong attraction to magnetic fields and maintain alignment even after the field is removed. Common examples of paramagnetic materials include aluminum, certain metal ions, and oxygen gas (O2).