XMCD reinvestigation of U2FeS5: an old material for modern science?

Altermagnets are promising materials for spintronics. Discovery of such compounds requires the reinvestigation of “old” materials with colinear magnetic structures, such as U2FeS5 where a ferromagnetic ordering of the Fe-atoms has been reported at T1 = 250 K and a second transition is observed at T2 = 18 K, corresponding to the ordering of the U-moments with a reorientation of the Fe ones. Moreover when our recent magnetic and spectroscopic (Mössbauer and HERFD-XANES at U M4 edge) studies of this compound are hardly compatible with the reported magnetic structure. The aim of this proposal is to determine precisely the magnetic contributions of all the elements in this uranium sulphide, as a function of temperature and magnetic field, using XMCD at U M4,5, Fe K and S K edges, in order to better understand the magnetic phase diagram. For this purpose, we expect dedicated beamtime on the ID12 beamline, where the expertise of beamline scientists on these elements will be of great interest.