Spin-wave measurements on MBE-grown zinc-blende structure MnTe by inelastic neutron scattering

Abstract

Spin-wave excitations of a MBE-grown single crystal of MnTe with a zinc-blende structure have been measured by inelastic neutron scattering in the type-III antiferromagnetic low-temperature phase of this compound. The experimental data have been modeled with a Heisenberg Hamiltonian including isotropic exchanges and magnetic anisotropy. Exchange constants and anisotropy terms have been estimated, which allowed a discussion on the relative importance of distant neighbors. The relevance of anisotropic exchanges is also discussed. The assumption of a collinear spin arrangement provides a consistent description of the spin-wave spectrum, including inelastic-neutron-scattering cross section. The temperature dependence of the spin waves revealed an anomalously strong damping, which starts well below the transition temperature.