Scientists unlock pure spin currents in altermagnets for faster computing

Scientists have successfully generated nearly 100% pure spin currents in an altermagnet, a material once thought unsuitable for this purpose. The breakthrough, led by Deepika Gill and researchers at the Max-Born-Institute and Rutherford Appleton Laboratory, opens new possibilities for spintronics and ultrafast data processing. The team focused on Cr₂SO, an altermagnet with a unique valley structure. By using linearly polarised infrared light, they selectively excited electrons in specific valleys of the material. This approach avoided unwanted excitation in other regions of the Brillouin zone.

A terahertz pulse then shifted the momentum of these electrons, preventing current cancellation. Unlike traditional methods, this technique bypassed the need for spin-orbit coupling, reducing intrinsic spin mixing. Temporal analysis later confirmed the absence of charge current after the pulse, proving the generation of highly efficient spin current. The combination of infrared valley excitation and terahertz manipulation achieved what was previously considered impossible in Cr₂SO. The process relied on a valley selection rule tied to the polarisation of light, eliminating the need for charge flow.

These findings expand the range of materials viable for spintronics applications. The ability to generate pure spin currents in altermagnets like Cr₂SO could accelerate the development of faster, more efficient data storage and processing technologies.