Scientists discover new, 3rd form of magnetism that may be the 'missing link' in the quest for superconductivity
04/02/2025
An abstract conceptual drawing showing how the new form of "altermagnetism" would work. (Image credit: Alex Speed, CC BY 4.0)
Researchers have obtained the first conclusive evidence of an elusive third class of magnetism, called altermagnetism. Their findings, published Dec. 11 in the journal Nature, could revolutionize the design of new high-speed magnetic memory devices and provide the missing puzzle piece in the development of better superconducting materials.
"We have previously had two well-established types of magnetism," study author Oliver Amin, a postdoctoral researcher at the University of Nottingham in the U.K., told Live Science. "Ferromagnetism, where the magnetic moments, which you can picture like small compass arrows on the atomic scale, all point in the same direction. And antiferromagnetism, where the neighboring magnetic moments point in opposite directions — you can picture that more like a chessboard of alternating white and black tiles."
Electron spins within an electrical current must point in one of two directions and can align with or against these magnetic moments to store or carry information, forming the basis of magnetic memory devices.
A new form of magnetism
Altermagnetic materials, first theorized in 2022, have a structure that sits somewhere in between. Each individual magnetic moment points in the opposite direction as its neighbor, as in an antiferromagnetic material. But each unit is slightly twisted relative to this adjacent magnetic atom, resulting in some ferromagnetic-like properties.
Altermagnets, therefore, combine the best properties of both ferromagnetic and antiferromagnetic materials. "The benefit of ferromagnets is that we have an easy way of reading and writing memory using these up or down domains," study co-author Alfred Dal Din, a doctoral student also at the University of Nottingham, told Live Science. "But because these materials have a net magnetism, that information is also easy to lose by wiping a magnet over it."
Conversely, antiferromagnetic materials are much more challenging to manipulate for information storage. Because they have a net zero magnetism, however, information in these materials is much more secure and faster to carry. "Altermagnets have the speed and resilience of an antiferromagnet, but they also have this important property of ferromagnets called time reversal symmetry breaking," Dal Din said.
This mind-bending property looks at the symmetry of objects moving forward and backward in time. "For example, gas particles fly around, randomly colliding and filling up the space," Amin said. "If you rewind time, that behavior looks no different."”
Source: https://tinyurl.com/mwh95k76 via Space