There are two main different types of magnet, permanent magnets and electromagnets. A permanent magnet is called a permanent magnet because its magnetism is ‘always on’, it generates its own persistent magnetic field unlike an electromagnet which is made from a coil of wire wrapped around a steel core and requires an electric current to generate a magnetic field. This article explains how a permanent magnet works.
How a permanent magnet works is all to do with its atomic structure
Ferromagnetic materials, the material that all magnets are made of (metals like iron, nickel and cobalt) have some unpaired electrons in their atoms. These electrons are always spinning and create their own magnetic field, albeit a very weak one.
A number of these atoms are grouped together to form individual magnetic domains, each with their own north and south poles so essentially each domain is like a tiny, tiny magnet! The image below depicts individual magnetic domains randomly aligned with their magnetic fields pointing in different directions.
When a magnet is manufactured an external magnetic field is applied to the raw material as it is heated and cooled forcing the individual domains to align with the direction of the external magnetic field. The majority of these domains then stay aligned once the external field is removed, as shown below.
As the majority of the domains are now pointing the same way (including their north and south poles) one whole permanent magnet is created with a preferred direction of magnetism. Magnets manufactured in this way are referred to as having an anisotropic alignment. A magnet is described as anisotropic if all of it’s magnetic domains are aligned in the same direction delivering maximum magnetic output. This direction is called the ‘magnetic axis’. Permanent magnets will maintain this alignment and their magnetism (known as remanence) indefinitely if kept in ideal conditions, for example not being allowed to corrode or not used in temperatures exceeding their maximum operating temperature.
Interested in finding out how the strongest magnets in the world are made? Read our article, how are neodymium magnets made?