Ligand-mediated Origin of Altermagnetic Spin-Splitting

Luigi Camerano; Federico Bisti; Gianni Profeta

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arXiv · 2605.21284

Ligand-mediated Origin of Altermagnetic Spin-Splitting

Luigi Camerano·Federico Bisti·Gianni Profeta

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Abstract

Altermagnets host spin-split electronic bands despite zero net magnetization, opening new routes for spintronics beyond conventional ferromagnets. Going beyond symmetry-based classifications, which specify allowed terms but not their hierarchy, here we use first-principles calculations and Wannier Hamiltonian engineering to uncover the microscopic bonding contributions of altermagnetic spin splitting in the $g$-wave altermagnet Co$_{1/4}$NbSe$_2$. We show that the splitting is captured by a short-range tight-binding model, establishing its local origin. By selectively controlling hopping channels, we demonstrate that the dominant contribution arises not from direct magnetic-ion hopping, but from ligand-mediated hybridization that transfers anisotropy to itinerant states. This identifies ligand-assisted coupling as the key mechanism of altermagnetic spin splitting and provides a microscopic bridge between minimal models and symmetry guided first-principles material searches, enabling real-space design of altermagnetic functionality.

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Luigi Camerano, Federico Bisti, Gianni Profeta. 2026-05-20. Ligand-mediated Origin of Altermagnetic Spin-Splitting. https://arxiv.org/abs/2605.21284

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