Researchers have identified altermagnetism, a third form of magnetism combining characteristics of ferromagnetism and antiferromagnetism, paving the way for advances in spintronics and superconductivity.
Altermagnetism is a new form of magnetism that combines the properties of ferromagnetism and antiferromagnetism. Recently discovered, it features a unique configuration of electron spins, making it possible to polarize an electric current without net magnetization. This discovery opens up promising prospects for the development of faster, more efficient spintronic devices, as well as for the improvement of superconducting materials.
A new form of magnetism
Until recently, two forms of magnetism were well established: ferromagnetism and antiferromagnetism. In ferromagnetic materials, the magnetic moments of the atoms, similar to small compass needles, align in parallel, generating a net magnetization. Conversely, in antiferromagnetic materials, these moments align antiparallel, cancelling out the overall magnetization. In 2022, researchers theorized a third form of magnetism, called altermagnetism. In this configuration, the magnetic moments of neighboring atoms point in opposite directions, but with a slight twist, giving the material hybrid properties between ferromagnetism and antiferromagnetism.
Unique properties of altermagnetic materials
Altermagnetic materials offer a unique combination of properties. Like antiferromagnetics, they have no net magnetization, making them robust to external disturbances and suitable for high-frequency applications. However, they also possess the ability to spin-polarize an electric current, a characteristic typical of ferromagnets. This polarization is due to a break in time-reversal symmetry, a property that enables the appearance of specific electrical phenomena.
Potential applications in spintronics
Spintronics is a field of research that exploits the spin of electrons, in addition to their charge, for information storage and processing. Altermagnetic materials offer significant advantages for this technology. Their ability to polarize electrical currents without net magnetization makes it possible to design memory devices that are faster, denser and less sensitive to external magnetic interference. For example, researchers have experimentally demonstrated the altermagnetic character of manganese silicide (Mn₅Si₃), a material composed of abundant and inexpensive elements, paving the way for potential industrial applications.
Implications for superconductivity
The discovery of altermagnetism could also have important implications for superconductivity, a phenomenon in which certain materials conduct electricity without resistance at very low temperatures. Altermagnetic materials could provide the missing link for understanding and developing new superconductors, particularly those requiring spin polarization. This deeper understanding of the interactions between magnetism and superconductivity could lead to the design of more efficient superconducting materials at higher temperatures.
The characterization and understanding of altermagnetic materials is still in its infancy. Further research efforts are needed to identify new materials with altermagnetic properties at room temperature, which is crucial for practical applications. In addition, the development of techniques to control and manipulate these properties at the nanometer level will be essential for integrating these materials into advanced technological devices. Interdisciplinary collaborations between physicists, chemists and engineers will be key to exploiting the full potential of altermagnetism in future technologies.
The discovery of altermagnetism represents a major breakthrough in the field of magnetism and opens up new prospects for spintronics and superconductivity. Future research will enable us to better understand this phenomenon and develop innovative applications in various technological sectors.
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