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arXiv · 2502.19815

Spontaneous magnon decay in two-dimensional altermagnets

Niklas Cichutek·Peter Kopietz·Andreas Rückriegel
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Abstract

We show that magnons in two-dimensional altermagnets can spontaneously decay at zero temperature. The decay rate is determined by quantum fluctuations and scattering processes involving the decay of a single magnon into three. These processes are kinematically allowed due to the convexity of the altermagnetic magnon dispersion. For small wavevectors $k$ the decay rate is proportional to $k^5$ with a direction-dependent prefactor which is maximal along the diagonals of the Brillouin zone. Moreover, for a given momentum only magnons with one specific chirality can spontaneously decay.

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Niklas Cichutek, Peter Kopietz, Andreas Rückriegel. 2025-02-27. Spontaneous magnon decay in two-dimensional altermagnets. https://doi.org/10.1103/b5vs-ldpm

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