Even though you've seen refrigerators covered in them, magnets are actually hard to come by. In fact, according to Duke University (DU), only about five percent of all known inorganic compounds exhibit even a little magnetism. So instead of searching the world for new magnets, researchers at the school and at Trinity College in Dublin have recently synthesized two of their own, from a list of 236,115 potential creations.
To be clear, magnets have been made in the lab before. But oftentimes, the process that leads to their genesis can be more of a hit-and-miss endeavor than an exacting science. To help give them an edge, the DU researchers turned, naturally, to a computer. Specifically, they worked with a computational model that let them try out different molecules in different arrangements for a class of materials called Heusler alloys, which consist of three different elements arranged in particular ways. Considering the range of possible elements (55) and atomic structures, the potential compounds numbered 236,115.
Using the model to see how different atoms and structures would react with each other, the researchers eventually whittled their list down to 22 possible candidates that could display magnetism, and then reduced that list to just 14 compounds by eliminating close relatives. Next it was time to make the materials in the lab, which was still a challenge, but an much easier one.
"It can take years to realize a way to create a new material in a lab," said Corey Oses, a DU doctoral student. "There can be all types of constraints or special conditions that are required for a material to stabilize. But choosing from 14 is a lot better than 200,000." Oses worked with Stefano Curtarolo, professor of mechanical engineering and materials science and director of the Center for Materials Genomics at Duke, on a paper that was recently published about the materials in the journal Science Advances.
The team relied upon Stefano Sanvito, professor of physics at Trinity College in Dublin, Ireland to actually produce the new magnetic materials, and, after years of attempts, he had success with with two.
The first consists of cobalt, manganese and titanium (Co2MnTi) and holds it magnetism to the impressive temperature of 938 K (1228° F), which could make it an idea candidate in a range of industrial applications.
The second is made of a mix of manganese, platinum and palladium (Mn2PtPd) and, although it doesn't actually produce a magnetic field of its own, it has electrons that react strongly to magnetic fields. This would make it a good candidate for use in hard drives although, beyond that, its use is somewhat limited because its behavior is difficult to predict.
Still, the researchers say that the function of the magnets isn't really as important as the fact that they were developed in the first place.
"It doesn't really matter if either of these new magnets proves useful in the future," said Curtarolo. "The ability to rapidly predict their existence is a major coup and will be invaluable to materials scientists moving forward."
Oses adds that the new computer model could also help the world move away from its reliance on rare-earth elements such as yttrium and neodymium, a common but hard-to-secure source of current magnets.
"Many high-performance permanent magnets contain rare earth elements," said Oses. "And rare earth materials can be expensive and difficult to acquire, particularly those that can only be found in Africa and China. The search for magnets free of rare-earth materials is critical, especially as the world seems to be shying away from globalization."
Source: Duke University