Magnets are the key material for many industries. Thanks to its development, many objects become smaller and smaller. Recently scientists from the University of Maryland (UMD) and Temple University have discovered a new class of magnet. The volume of this novel magnet will expand in a magnetic field; but it wastes little heat which can be ignored during collecting energy. The new discovery has huge market potential to replace existing technology, as well as create new application.

Magnetostrictive Effect
In 1842, British physicist James Joule found that the iron-based magnetic materials can change their volume or length during the process of magnetization. But this change is very small and the change for volume is much smaller than the length change. It is a property of ferromagnetic materials and called magnetostrictive effect which causes losses due to frictional heating in susceptible ferromagnetic cores, at the same time it can be used as the low-pitched humming sound that can be heard coming from transformers.

No Magnetic Field

Magnetic Field Applied

Non-Joulian Magnets
The new magnet is "non-Joulian magnets” due to huge change in volume. The iron-based alloys through heat treatment (heated to 760º C (1,400º F) for 30 minutes before cooled down to room temperature rapidly) in a furnace appear a special tiny honeycomb-like structure. This structure is the key of non-Joulian magnetostriction and can help researchers to develop new material with similarly attractive characteristics.

The researchers pointed out that, limited by magnetostrictive effect, the traditional magnet only can be applied in the actuator which works in one direction. Even if for actuator braked in two directions, it’s also required lots of heavy magnets, which increases the product volume and reduces efficiency. However "non-Joulian magnets” simultaneously expanding in all directions, compact omnidirectional actuator would be easy to implement.Because of energy-saving feature of new magnet, it can be used to create a new generation of low heat loss sensors and actuators used in aerospace, automotive, biomedical, defense, space exploration and robotics.

The researchers also said that the new magnets don’t contain rare earth elements, which can replace existing expensive but low mechanical properties of rare-earth element magnets.

The results of this research were recently published in the journal Nature.