March 28, 2025 -- Recently, a group of researchers led by Prof. QU Zhe from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, together with Prof. CHANG Tay-Rong from National Cheng Kung Universityhas discovered a novel way to achieve spin-valve effects using kagome quantum magnets.

"This approach uses a prototype device made from the kagome magnet TmMn₆Sn₆," explained Associate Prof. XU Xitong, "This breakthrough eliminates the need for the complex fabrication techniques traditionally required by spin-valve structures."

The finding was published in Nature Communications.

Spin-valve devices, widely used in magnetic sensing, typically consist of a trilayer structure of ferromagnetic layer/nonmagnetic spacer/ferromagnetic layer. This structure modulates spin scattering strength by controlling the relative magnetic orientation of the ferromagnetic layers, enabling a spin-dependent transport effect called the giant magnetoresistance. However, traditional sandwich-structured spin-valve devices require complex fabrication processes such as atomic-level flat epitaxial growth, sputtering deposition, or precise mechanical stacking of van der Waals heterostructures, posing challenges in stability and scalability.

To address these limitations, the research team proposed a novel mechanism that takes advantage of the unique interlayer interactions in kagome helimagnets. By applying an external magnetic field, they induced a special parallel multidomain state in the kagome magnet TmMn₆Sn₆, effectively replicating the behavior of traditional spin-valve structures—without the need for complex material stacking.

Transport measurements on their prototype device revealed a giant magnetoresistance effect exceeding 160%. Additionally, magnetic force microscopy imaging at the High Magnetic Field Laboratory confirmed that this effect originates from domain-wall scattering.

Further theoretical analysis showed that the spin-valve effect in kagome helimagnets offers high tunability, opening exciting possibilities for future spintronic applications.

This study offers new avenues for developing low-power-consumption spintronic devices based on quantum magnets, according to the team.