Instability of magnons in two-dimensional antiferromagnets at high magnetic fields

Masuda, Takatsugu*; Kitaoka, Shuji*; Takamizawa, Satoshi*; Metoki, Naoto; Kaneko, Koji; Rule, K. C.*; Kiefer, K.*; Manaka, Hiroshi*; Nojiri, Hiroyuki*

Physical Review B, 81(10), p.100402_1 - 100402_4, 2010/00

https://doi.org/10.1103/PhysRevB.81.100402

Spin dynamics of the square lattice Heisenberg antiferromagnet, BaMnGeO, is studied by a combination of bulk measurements, neutron diffraction, and inelastic neutron-scattering techniques. Easy plane type antiferromagnetic order is identified at T4.0 K. The exchange interactions are estimated as = 27.8(3) eV and = 1.0(1) eV, and the saturation field is 9.75 T. Magnetic excitation measurements with high experimental resolution setup by triple axis neutron spectrometer reveals the instability of one magnon excitation in the field range of 0.7 0.85.