Magneto structural transition in the DySi CrB- and micro-structural changes in the FeB-type compounds by XRPD and neutron diffraction

► Unusual magneto structural transition in dimorphic DySi (FeB- and CrB-type, TN=40 K) at T2=23.5 K. ► Electron microscopy shows no intergrowth domains of the strongly related FeB- and CrB-type phases. ► Unusual transition in FeB HT phase q disproportionates below T2→2 K into two magnetic phases q→q1+q2. ► X-ray, neutron diffraction relate this phenomenon to a 1st order minor monoclinic distortion at T2. ► The parent HT and LT FeB structures presumably coexist from T2→2 K with distinct magnetic structures.