Zero Net Magnetization
Although each spin creates a tiny magnetic field on a microscopic view, the net magnetization
or macroscopic magnetization is usually zero because all the individual spins are oriented
randomly and cancel each other's fields. An example of this can be shown in the picture of the
un-aligned spins below.
Un-aligned spins
Alignment in a large external magnetic field
When particles are placed in a large external magnetic field (B) their spins will align with the
magnetic field. Most of the spins will align with the magnetic field (parallel), as that is
the lower-energy option. However, a few will align against the external field (anti-parallel)
if they are at a higher energy. When large groups of spins have aligned, either parallel or
anti-parallel, a net magnetization is present.
Aligned spins
Further Reading
