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

We present the classical antiferromagnet MnF\u2082 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.Nous pr\ue9sentons l\u2019antiferromagn\ue9tique MnF\u2082 comme un exemple p\ue9dagogique parfait pour montrer une foule de concepts en diffusion de neutrons. Nous analysons la nature de l\u2019antiferromagn\ue9tisme et le hamiltonien magne\ub4tique de ce sp\ue9cimen antiferromagn\ue9tique. Nous d\ue9terminons exp\ue9rimentalement la temp\ue9rature de transition de N\ue9el, la valeur du moment magn\ue9tique dans l\u2019\ue9tat ordonn\ue9, la diffusion critique pr\ue8s de la transition de phase, les ondes de spin associ\ue9es \ue0 la mise en ordre des moments, aussi bien que leur dispersion et leur d\ue9pendance en temp\ue9rature. Les param\ue8tres obtenus ici, comme la temp\ue9rature de transition de N\ue9el et les constantes du couplage d\u2019\ue9change sont en assez bon accord avec les valeurs d\ue9j\ue0 publi\ue9es. De plus, nous pr\ue9sentons de fa\ue7on d\ue9taill\ue9e la diffusion de neutrons \ue0 l\u2019aide d\u2019un spectrographe \ue0 trois axes.Peer reviewed: YesNRC publication: Ye