ECA lunchtime webinars – Neutron scattering
L’Association Européenne de Cristallographie (ECA) organise depuis 2021 des “webinaires déjeuner”. Les groupes d’intérêt spéciaux (SIG) et les groupes d’intérêt général (GIG) de l’ECA organisent à tour de rôle un webinaire adapté à la communauté des cristallographes au sens large. Le dix-huitième webinaire sera diffusé le 2 février 2023 avec deux conférences: Fundamentals of neutron scattering par Henrik Rønnow (EPFL, Suisse) et Recent advancements in magnetic neutron diffraction: detection of inversion-symmetry breaking local magneto-electric multipoles par Jian-Rui Soh (EPFL, Suisse).
Abstract of the lecture by Jian-Rui Soh: The fundamental interaction between the neutron dipolar field and the magnetisation density surrounding the scattering ion, lies at the heart of magnetic neutron diffraction. However, if the ion resides in an environment which breaks both time and spatial inversion symmetry, the current formalism for magnetic diffraction does not fully account for all the possible scattering mechanisms arising from the asymmetry of the magnetisation density cloud of the scatterer. In our work, we have (i) extended the theory of magnetic neutron diffraction to include these effects, (ii) developed a framework to calculate the associated neutron cross sections using density functional theory and (iii) employed spherical neutron polarimetry to provide direct experimental evidence for these multipoles in CuO.
EPFL, Suisse