Altermagnetism was first theorized in 2019 and experimentally confirmed in 2024 by researchers at Mainz University. It bridges the gap between traditional magnetic classifications, offering practical applications in advanced data storage systems.
Top Scientific Breakthroughs of 2024
Science and research continuously deliver groundbreaking discoveries, expanding the boundaries of what we know. Each year, the renowned journal Science highlights ten of these achievements in its list of top scientific breakthroughs. For 2024, the journal named the drug lenacapavir — hailed for its potential to reduce HIV/AIDS infections to zero — as the Breakthrough of the Year. In the realm of physics, another major milestone was recognized: the discovery of altermagnetism by researchers at Johannes Gutenberg University Mainz (JGU).
“This is a truly unique tribute to our work, and we are proud and honored to receive this acknowledgment for our research,” said Professor Jairo Sinova of the JGU Institute of Physics. He and his team discovered and demonstrated the phenomenon of altermagnetism.
Until now, physics recognized only two types of magnetism: ferromagnetism and antiferromagnetism. Ferromagnetism, known since ancient Greece, is the force that makes refrigerator magnets stick, where all magnetic moments align in the same direction. Antiferromagnetism, on the other hand, involves magnetic moments aligning in a regular pattern but pointing in opposite directions, canceling each other out externally.
Theoretical Prediction of Altermagnetism
In 2019, researchers at Mainz University came across an effect that they could not explain by either of these types of magnetism: the presence of a fully intact momentum current in antiferromagnets. They postulated that this must be attributable to an alignment of magnetic moments that was unlike that in ferromagnetism and antiferromagnetism – and with that, the concept of altermagnetism was born.
In effect, altermagnets combine the characteristics of ferromagnets and antiferromagnets. Their neighboring magnetic moments are always antiparallel to each other, as in antiferromagnets, but, at the same time, they exhibit a spin-polarized current – just like ferromagnets.
“By means of a mathematical analysis of the spin symmetries, we were able to theoretically predict the existence of altermagnetism,” explained Professor Sinova. “The spin-polarized current alternates with the direction of the current, hence the name ‘altermagnetism’.”
The new field of altermagnetism is at the core of the Collaborative Research Centers CRC/TR 173 “Spin+X – Spin in its collective environment” and CRC/TR 288 “Elastic Tuning and Response of Electronic Quantum Phases of Matter” (ELASTO-Q-MAT), in which JGU researchers play a significant role. The German Research Foundation approved continued funding for both CRCs in 2024.
Experimental Validation in 2024
In 2024, the researchers at JGU also obtained experimental demonstration of altermagnetism. “Our colleagues in the team of Professor Hans-Joachim Elmers were able to measure for the first time an effect that is considered to be a signature of altermagnetism. They used a specially developed impulse electron microscope at DESY, one of Germany’s largest research centers,” added Sinova.
The discovery of altermagnetism as a third type of magnetism is an important scientific breakthrough because it reveals an effect that was previously unknown but even more so because of the relevance of the practical applications in which it could be used. Data storage capacity could be substantially increased if it proves feasible to use the magnetic moment of electrons instead of their charge in dynamic random-access memory for data storage. The big advantage is that there are at least 200 different materials that are currently known to exhibit altermagnetism.
