Irreducible Representation Dimensionality Determines Coupling Hierarchy and Fragility in Collinear Altermagnets

Irreducible Representation Dimensionality Determines Coupling Hierarchy and Fragility in Collinear Altermagnets | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Irreducible Representation Dimensionality Determines Coupling Hierarchy and Fragility in Collinear Altermagnets Amor Toumiat, nedjla rouidi, ouahiba halimi, abdelghani may This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8745493/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Altermagnetism has emerged as a fundamental magnetic phase, yet experimental signatures remain starkly inconsistent across material classes. While hexagonal systems exhibit robust, giant spin splitting, signatures in rutile and cubic candidates appear fragile and sensitive to sample quality. Here, we resolve this dichotomy by deriving a universal fragility index, F=n⋅"dim" (Γ^- ), based on the dimensionality of the time-reversal-odd irreducible representation. We demonstrate that the coupling exponent n is a symmetry-enforced consequence of the irrep’s dimension, dictating a critical scaling law g_k∨∝(T_"N" -T)^nβ. This parameter-free framework identifies RuO2 as an inherently fragile n=2 system compared to robust n=1 pnictides. Furthermore, we provide a roadmap for fragility engineering, showing how strain and dimensionality reduction through specific cleavage planes like (110) can stabilize elusive phases. Our results provide a model-independent diagnostic for altermagnetic robustness, offering a transformative principle for the discovery and design of stable spintronic materials. Magnetism Altermagnetism fragility irreducible representation Full Text Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8745493","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":590429658,"identity":"8a76b811-777f-4550-bd21-07a41386da5b","order_by":0,"name":"Amor 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While hexagonal systems exhibit robust, giant spin splitting, signatures in rutile and cubic candidates appear fragile and sensitive to sample quality. Here, we resolve this dichotomy by deriving a universal fragility index, F=n⋅\"dim\" (Γ^- ), based on the dimensionality of the time-reversal-odd irreducible representation. We demonstrate that the coupling exponent n is a symmetry-enforced consequence of the irrep’s dimension, dictating a critical scaling law g_k∨∝(T_\"N\" -T)^nβ. This parameter-free framework identifies RuO2 as an inherently fragile n=2 system compared to robust n=1 pnictides. Furthermore, we provide a roadmap for fragility engineering, showing how strain and dimensionality reduction through specific cleavage planes like (110) can stabilize elusive phases. 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