There are three main classes of Magnetic materials:
- paramagnetic
- ferromagnetic
- diamagnetic
The magnetic properties of matter form due to the intrinsic magnetic dipole moment in the atoms of the material#tosee .
Paramagnetism
Formed when the atoms in the element have a net non-zero magnetic dipole moment. Normally, theses dipole moments are randomly aligned.
They do get a superposed direction in presence of an external Magnetic Field, but it’s only partially aligned, so it’s generally weak.
Examples: Lithium, Aluminium, Titanium
Ferromagnetism
Formed when atoms have a permanent dipole moment, and theses moments are mostly aligned with each other, allowing the material to easily enhance a magnetic field.
Something to do with quantum exchange#tosee
Ferromagnets remain magnetised for a long period of time after the external field is removed.
Diamagnetism
All common materials (including humans) exhibit diamagnetism but it is a very small effect and is usually weaker than paramagnetism or ferromagnetism. In materials that only exhibit diamagnetism:
- No B-field: atoms do not have net magnetic dipole moment.
- External B-field: Dipoles are induced when material immersed inexternal B-field.
- Dipoles point in opposite direction to that of external field.