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Instability of antiferromagnetic magnons in strong fields

M. E. Zhitomirsky·A. L. Chernyshev
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Abstract

We predict that spin-waves in an ordered quantum antiferromagnet (AFM) in a strong magnetic field become unstable with respect to spontaneous two-magnon decays. At zero temperature, the instability occurs between the threshold field $H^*$ and the saturation field $H_c$. As an example, we investigate the high-field dynamics of a Heisenberg antiferromagnet on a square lattice and show that the single-magnon branch of the spectrum disappears in the most part of the Brillouin zone.

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M. E. Zhitomirsky, A. L. Chernyshev. 1999-05-11. Instability of antiferromagnetic magnons in strong fields. https://doi.org/10.1103/physrevlett.82.4536

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