Scientists discovered a new kind of behavior in magnetic materials when they are heated up. When the temperature rises, magnetic spins freeze into a static pattern. This is a phenomenon that usually occurs when the temperature drops. Their findings were published in Nature Physics on July 4.
Researchers discovered the phenomenon in the element neodymium. They had previously described it as "self-induced spun glass" several years ago. Spin glasses are alloys in which iron atoms are mixed randomly into a grid of copper. Each iron atom acts like a small magnet or spin. These spins can point in many directions.
Neodymium, unlike conventional spin glasses that have random mixing of magnetic materials and crystalline forms, is an element. The spins create patterns that look like a helix and this whirling can be random and change constantly.
When heated, solid pattern
Researchers discovered that neodymium heated up to 268 C (-265 C) causes the spins to "freeze", forming a type magnet at the higher temperature. The random whirling patterns of helixes returned when the material was cooled down. Alexander Khajetoorians from Radboud University, professor of scanning probe microscopy, says that the pattern's "freezing" does not usually occur in magnetic materials.
Temperature can increase the energy of a liquid, solid, or gas. The same is true for magnets: spins begin to shake when there's more temperature. "The magnetic behavior observed in neodymium is contrary to what happens 'normally. It is quite counterintuitive. "It's like water melting into ice cubes when heated up," Khajetoorians says.
These phenomena are rare in nature. It is rare that materials behave badly. Rochelle salt is another well-known example. At higher temperatures, the charges form an ordered pattern, while at lower temperatures they are randomly distributed.
How it works
Parisi was awarded the Nobel Prize in Physics in Physics in 2021 for his complex theoretical description and spin glasses. It is also important for other scientific fields to understand how spin glasses work. "If we can model the behavior of these materials, it could be applied to a variety of other materials."
The root cause of the odd behavior was degeneracy. This is when many states have the same amount of energy and the system becomes frustrated. Temperature has the ability to change this situation: some states survive and allow the system to settle into a single pattern. This behavior may be harnessed to create new information storage and computational concepts such as brain-like computation.
