If every iron atom is a tiny magnet why aren't all iron materials themselves magnets?
To understand why not all iron materials are magnets, it's important to know that the magnetic properties of a material depend on two factors: the alignment of the individual magnetic moments of its atoms and the presence of an external magnetic field.
In iron, each atom acts as a tiny magnet due to its unpaired electrons, which have intrinsic magnetic moments. These magnetic moments align in such a way that neighboring atoms reinforce each other's magnetic fields, creating small regions called magnetic domains. In a non-magnetized piece of iron, these domains are randomly oriented, resulting in a net magnetic moment of zero.
To turn an iron material into a magnet, we need to align the magnetic domains so that their magnetic moments collectively add up to produce a macroscopic magnetic field. This can be achieved through a process called magnetization. There are a few ways to magnetize iron, but one common method is applying an external magnetic field. When an external magnetic field is applied to the iron, the magnetic domains align with the field, leading to a temporary magnetization. However, once the external field is removed, the domains may revert to their random orientations, and the iron loses its magnetism.
Certain iron materials, such as iron alloys containing elements like cobalt or nickel, have more stable magnetic domains, allowing them to retain their magnetism even after the external field is removed. These materials are called permanent magnets. Moreover, the manufacturing process used to create permanent magnets aligns the domains, resulting in a more durable and stronger magnetic field.
So, the reason why not all iron materials are magnets is that their magnetic domains are not naturally aligned or stabilized to create a net macroscopic magnetic field.