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Phys. Rev. Lett. 82, 4536–4539 (1999)

Instability of Antiferromagnetic Magnons in Strong Fields

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M. E. Zhitomirsky1,2 and A. L. Chernyshev3,*
1Department of Physics, University of Toronto, Toronto, Canada M5S 1A7
2L. D. Landau Institute for Theoretical Physics, Moscow 117334, Russia
3Department of Physics, Queen's University, Kingston, Canada K7L 3N6

Received 10 August 1998; published in the issue dated 31 May 1999

We predict that spin waves in an ordered quantum antiferromagnet 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 Hc. 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 most of the Brillouin zone.

© 1999 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.82.4536
DOI:
10.1103/PhysRevLett.82.4536
PACS:
75.10.Jm, 75.50.Ee

*On leave from the Institute of Semiconductor Physics, Novosibirsk, 630090, Russia.

 
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