Magnetism has been a significant driver of progress, enabling everything from data writing to energy-saving devices. Now, scientists have discovered a third type of magnetism, altermagnetism, which has similarities to both ferromagnetism and antiferromagnetism. This magnetism has the potential to transform high-speed memory devices and offer important insights into superconductivity.
Altermagnets: Connecting ferromagnetism and antiferromagnetism
For decades scientists have known of two kinds of magnetism that dominate: ferromagnetism and antiferromagnetism. The atomic magnetic moments of ferromagnetic materials, for example: iron and nickel, align along the same direction, and this property is useful for information storage. Antiferromagnetic materials, in contrast, possess opposing moments that cancels out any net magnetization. This makes them impervious to outside interference but practically difficult to exploit.
Altermagnets bridge this gap. In these materials, the atomic magnetic (like this magnetic force which is generated by electrons) moments are aligned anti-parallel, akin to antiferromagnets, but they have a slight twist in their crystal structure.
This unique configuration can be condensed on the nano-scale, allowing for the resilience and speed of antiferromagnets and maintaining some of the information-storing capabilities of the ferromagnet. This hybrid magnetism opens new possibilities for electronic or computing developments in the future.
New altermagnetism discovered with vortex patterns in manganese telluride
A team of scientists, including researchers from the University of Nottingham, provided the first real evidence of altermagnetism. They applied a technique known as photo-emission electron microscopy to manganese telluride, a material that is believed to be purely antiferromagnetic.
By blasting polarized X-rays into the ultra-thin materials at MAX IV Laboratory in Sweden, researchers can visualize the proprietary magnetic vortices that are a defining feature of altermagnetism. Manipulating the internal structure of the material led to the creation of novel vortex patterns in hexagonal and triangular devices.
These vortices are becoming increasingly popular in spintronics for information carriers. Their discovery is a key step to incorporating altermagnetic materials into next-generation memory devices that can provide high speeds and enhanced protection against data loss.
Einstein–de Haas effect revolutionizes perspectives on altermagnetism
A central characteristic of magnetism is the Einstein–de Haas (EH) effect, which is a direct coupling of magnetism with atomic angular momentum. The phenomenon, discovered by Albert Einstein and Wander de Haas in 1915, demonstrates that flipping the magnetization of a material will cause the material’s atoms to rotate in response.
This is because the total angular momentum of a system must be conserved so that changes in electron spin affect the motion of the whole material. The Einstein–de Haas effect, which is particularly relevant to altermagnetism, demonstrates how controlling the spin of electrons can create mechanical motion.
This principle could be used to harness future applications of altermagnetic materials that can be optimized and adjusted for greater control over magnetic properties. Grasping this effect could help physicists search for new functionality with altermagnetic materials that could revolutionize energy transfer and potentially computing at the quantum level.
It is more than a purely academic breakthrough, however, as the discovery of altermagnetism has important applications in technology and materials science. Researchers think it may contain the missing link between magnetism and superconductivity, one of the longest-standing dilemmas about how electrons move in such extreme conditions.
Altermagnets could, with further study, create faster and more efficient electronic devices, opening the door to a new generation of high-performance computing. With these new materials being discovered, physicists are constantly studying the unique characteristics of magnetism and the future of this third type of magnetism looks bright.
Manipulation of such altermagnetic structures can open exciting new doors in various research areas including electronics, quantum computing, and more (like the first eolic cell with magnetic levitation). This discovery will bring magnetic research to a new frontier.
