Researchers have discovered a groundbreaking third form of magnetism, known as altermagnetism, which promises to revolutionize the field of spintronics and the development of new superconducting materials. This pioneering work, led by Professor Peter Wadley from the University of Nottingham, provides the first conclusive evidence of altermagnetism through the study of manganese telluride, a material long thought to be antiferromagnetic. The team's findings, published in the journal Nature, could significantly impact high-speed magnetic memory devices.
Altermagnetic materials occupy a unique position between ferromagnetic and antiferromagnetic materials. While they boast the speed and resilience of an antiferromagnet, they also exhibit a crucial characteristic of ferromagnets known as time reversal symmetry breaking. This property allows electron spins in an electrical current to align with or against magnetic moments to store or carry information.
"Ferromagnetism, where the magnetic moments, which you can picture like small compass arrows on the atomic scale, all point in the same direction." – Oliver Amin
"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." – Oliver Amin
The research team employed photoemission electron microscopy to examine manganese telluride's structure and magnetic properties, leading to the first-ever map of altermagnetic domains and structures. This technique revealed exotic vortex textures in both hexagonal and triangular devices within the material.
"Different aspects of the magnetism become illuminated depending on the polarization of the X-rays we choose," – Oliver Amin
"Circularly polarized light revealed the different magnetic domains created by the time reversal symmetry breaking, while horizontally or vertically polarized X-rays allowed the team to measure the direction of the magnetic moments throughout the material." – Oliver Amin
Altermagnets present a net zero magnetism, which enhances information security and speed. In contrast to ferromagnets, where information is vulnerable to loss by external magnetic influences, altermagnets offer a more secure medium for storing and carrying information.
"The benefit of ferromagnets is that we have an easy way of reading and writing memory using these up or down domains," – Alfred Dal Din
"But because these materials have a net magnetism, that information is also easy to lose by wiping a magnet over it." – Alfred Dal Din
The introduction of altermagnetism could prove to be a missing puzzle piece in developing superior superconducting materials. These findings have sparked increasing interest in altermagnetic materials as potential carriers of information within spintronics.
"Altermagnets have the speed and resilience of an antiferromagnet, but they also have this important property of ferromagnets called time reversal symmetry breaking," – Alfred Dal Din
"If you look at those two electron systems — one where time is progressing normally and one where you're in rewind — they look different, so the symmetry is broken," – Oliver Amin
The implications of this discovery extend beyond memory devices. The ability to manipulate electron spins and magnetic domains with precision could lead to advances in superconductivity, ultimately paving the way for more efficient electronic devices.
