The origin of magnetism in a supposedly nonmagnetic osmium oxide

Despite the fact that a system characterized by a 5d1 spin-orbit-coupled electronic configuration should be
nonmagnetic and metallic, Ba2NaOsO6 is a Mott insulator and develops a canted ferromagnetic long-range
order. Ab-initio quantum chemical calculations show that the magnetic moment rapidly increases in the
presence of compressive distortions. However, preliminary EXAFS and NMR measurements do not
provide evidence of such structural distortions at room temperature. We therefore aim to directly probe the
electronic structure of Ba2Na1-xCaxOsO6 by means of RIXS; in particular, we will monitor d-d excitations
as fingerprints of the effective crystal field symmetry and possibly determine the origin of its unexpected
transport and magnetic properties