Hyperspin Ferromagnets

Abstract:The behavior of spin quantum in k-space is key to identifying altermagnets (AMs) as the third kind of fundamental collinear magnetism. In contrast, non-collinear magnets,though abundant in nature,lack well-defined spin quantum numbers, and the resulting spin textures are often highly complex, which limits their potential for next-generation spintronic applications. Here we propose hyperspin, which lives in a higher-dimensional space, to address these drawbacks. Through analyzing the commutation relations between spin and Hamiltonian for a class of non-collinear magnets, we reveal it is a hyperspin, rather than the usual spin, that commutes with Hamiltonian. Unexpectedly, these non-collinear magnets should also show collinear spin-split bands in k-space like collinear AMs. We therefore classify such non-collinear magnets as hyperspin altermagnets (HAMs), as opposed to the usual collinear AMs. Our theory elucidates the fundamental physics of AMs and HAMs and provides a framework for exploring the wide range of non-collinear magnets that may possess other kinds of conserved quantities.

Materials Science (cond-mat.mtrl-sci); Other Condensed Matter (cond-mat.other); Quantum Physics (quant-ph)

arXiv:2609.10930 [cond-mat.mtrl-sci]

(or arXiv:2609.10930v1 [cond-mat.mtrl-sci] for this version)

https://doi.org/10.48550/arXiv.2609.10930 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

Phys. Rev. Lett. 137, 116704 (2026)

https://doi.org/10.1103/dnr2-gv31 Focus to learn more DOI(s) linking to related resources

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