In the 1840s, British physicist James Joule discovered that iron-based magnetic materials would change their shape but maintain their volume when placed in a magnetic field. This phenomenon is called "Joule magnetostriction", and in the 175 years since its discovery, all magnets have exhibited this characteristic.

According to Science and Technology Daily, researchers from Temple University and the University of Maryland in the United States have discovered a new type of magnet. They heated a specific iron-based alloy in a furnace to approximately 760 degrees Celsius for 30 minutes, then rapidly cooled it to room temperature. When the material was placed in a magnetic field, it exhibited non Joule magnetostriction behavior (expansion).

Researchers point out that due to the limitations of Joule magnetostriction, conventional magnets can only be used as actuators to apply force in one direction. Even if only actuated in two directions, a large number of bulky magnets are required, which increases volume and reduces efficiency. Non Joule magnetostrictive magnets can expand in all directions simultaneously, making it easy to manufacture compact omnidirectional actuators.

Due to their energy-saving properties, these new magnets can be used to create a new generation of sensors and actuators with extremely low heat loss, which are applied in fields such as aerospace, automotive, biomedicine, national defense, space exploration, and robotics.

The researchers also stated that this new type of magnet does not contain rare earth elements, and therefore can replace existing expensive but low mechanical performance rare earth based magnetostrictive materials.

It is reported that this achievement was published in an issue of the journal Nature.