Breakthrough discovery of third form of magnetism could unlock superconductivity secrets

In a major breakthrough that could help solve the longstanding puzzle surrounding superconductors, scientists have uncovered the first conclusive evidence of the elusive third category of magnetism — altermagnetism.

Researchers believe this discovery could revolutionise the design of new high-speed magnetic memory devices and provide a crucial piece of the puzzle in developing better superconducting materials, as reported by Live Science.

Discussing their latest study, published in Nature journal on December 11, 2024, lead author Oliver Amin explained how, until now, two well-established types of magnetism were known.

Ferromagnetism and antiferromagnetism

Amin explained that ferromagnetism occurs when magnetic moments can be visualised as small compass arrows on the atomic scale, all pointing in the same direction.

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Conversely, antiferromagnetism is when neighbouring magnetic moments point in opposite directions. This can be pictured like a chessboard, with alternating white and black tiles.

First theorised in 2022, altermagnetic materials have a structure that falls between the other two.

Similar to antiferromagnetic materials, each magnetic moment points in the opposite direction of its neighbour. However, in altermagnets, each unit is slightly twisted relative to the adjacent magnetic atom, resulting in properties similar to ferromagnetism.

Thus, altermagnets combine the best properties of both ferromagnetic and antiferromagnetic materials.

Alfred Dal Din, a co-author of the study and a doctoral student at the University of Nottingham, noted that ferromagnets allow easy reading and writing of memory using these up or down domains.

However, he added, this information is vulnerable to being wiped away by a magnet, as these materials possess net magnetism.

Dal Din further explained that altermagnets have the time-reversal symmetry breaking property of antiferromagnets, coupled with the speed and resilience of ferromagnets.

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Missing link in superconductivity

During their study, the team used photoemission electron microscopy to analyse the structure and magnetic properties of manganese telluride, which was previously thought to be antiferromagnetic.

Amin, a postdoctoral researcher at the University of Nottingham, revealed that their research uncovered how various aspects of the material’s magnetism are “illuminated depending on the polarisation of the X-rays we choose.”

FAQs

⁠What's the third form of magnetism?
Altermagnetism is the third form of magnetism.

⁠What are the three forms of magnetism?
The three forms of magnetism are ferromagnetism, antiferromagnetism and altermagnetism.