Neutron scattering study of the classical antiferromagnet MnF2: A perfect hands-on neutron scattering teaching course

Abstract

We present the classical antiferromagnet MnF2 as a perfect demonstration system for teaching a remarkably wide variety of neutron scattering concepts. The nature of antiferromagnetism and the magnetic Hamiltonian in this classical antiferromagnet are discussed. The transition temperature to the Neel state, the value of magnetic moment in the ordered state, the critical scattering close to the phase transition, spin waves associated with the ordering of the moments, as well as their dispersion and temperature dependences are determined experimentally. Parameters such as the Neel transition temperature and exchange coupling constants obtained from the experiments agree reasonably well with the previously published data. In addition, details of how an inelastic neutron scattering experiment is performed by means of triple-axis spectroscopy are provided.