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arXiv · 2511.16086

Coherent high-velocity chiral magnons in the metallic altermagnet CrSb

Ashutosh K. Singh·Niclas Heinsdorf·Abraham A. Mancilla·Jörn Bannies·Avishek Maity·Alexander I. Kolesnikov·Masaaki Matsuda·Matthew B. Stone·Marcel Franz·Jonathan Gaudet·Alannah M. Hallas
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Abstract

We report the collective magnetism of the metallic altermagnet CrSb. Magnetic susceptibility and polarized neutron diffraction measurements show that CrSb is a perfectly compensated Ising altermagnet below a Néel temperature of $T_N = 733(4)$ K. Inelastic neutron scattering experiments reveal coherent and highly-dispersive antiferromagnetic spin waves with large group velocities of 61(2) km s$^{-1}$ and 58(2) km s$^{-1}$ along the in-plane and out-of-plane directions, respectively. The observed magnon dispersions along high-symmetry directions of the Brillouin zone are well described by a minimal Heisenberg model up to third nearest neighbors of alternating antiferromagnetic and ferromagnetic character, $J_1 = 23(4)$ meV, $J_2 = -5.4(8)$ meV, $J_3 = 5.2(8)$ meV, and an Ising single-ion anisotropy term $D = 0.15(4)$ meV. We observe clear momentum space signatures of chiral spin splitting along the low-symmetry $Γ$-$L$ direction, characteristic of higher-order altermagnetic exchange interactions, the first such observation in a metallic altermagnet. These findings identify CrSb as a singular material: a metallic altermagnet in which coherent spin-split magnons persist well above room temperature, providing a compelling platform for spintronic applications.

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Ashutosh K. Singh, Niclas Heinsdorf, Abraham A. Mancilla, Jörn Bannies, Avishek Maity, Alexander I. Kolesnikov, Masaaki Matsuda, Matthew B. Stone, Marcel Franz, Jonathan Gaudet, Alannah M. Hallas. 2026-05-13. Coherent high-velocity chiral magnons in the metallic altermagnet CrSb. https://arxiv.org/abs/2511.16086

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