Scientists have discovered magnetic material that "freezes" when heated

Credit image: public domain - neodymium
Credit image: public domain - neodymium

Article by: Andacs Robert Eugen, on 10 July 2022, at 10:05 am Los Angeles time

When the magnetic materials are cooled to the right temperature, something interesting happens. The rotations of their atoms, "freeze" and lock in a static pattern, exhibiting a cooperative behavior that does not usually manifest itself.

Now, for the first time, physicists have noticed the opposite. When heated fractionally, the natural magnetic element called neodymium freezes, upsetting all our expectations.

"The magnetic behavior of neodymium that we have now observed is actually the opposite of what normally happens," said physicist Alexander Khajetoorians of Radboud University in the Netherlands.

"It's quite counterintuitive, like water which, in this scenario, would become an ice cube when heated."

In a conventional ferromagnetic material, such as iron, the magnetic spins of the atoms all align in the same direction. This means that the north and south magnetic poles are oriented in the same way in three-dimensional space.

When a material is heated, the increase in temperature also determines the amplification of the energy in that material. In the case of magnets, this increases the movement of the spines. But the opposite also happens: when a magnet is cooled, the rotations slow down.

In this context, a team of scientists wanted to investigate how neodymium behaves at varying temperatures. Interestingly, they found that raising the temperature of the neodymium from -268 degrees Celsius to -265 degrees Celsius (-450.4 to -445 Fahrenheit) induced frost.

It is not clear why this happens, because it is very rare for a natural material to behave in a "wrong" way, as opposed to the way all other materials of this type behave.

Subsequent investigations could reveal the mechanism behind this strange behavior, and researchers note that this has implications that go far beyond the realm of physics.

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