Neutron diffraction study of the La1-xYxMn2Si2 solid solution (O≤x≤Z)

The La1-xYxMn2Si2 compounds (0<x less than or equal to 1) have been investigated by powder neutron diffraction. For x<0.5, the low temperature magnetic structures are characterized by mixed planes where both ferro-and antiferromagnetic components coexist while for x greater than or equal to 0.5, ferromagnetic Mn planes prevail. The in-plane ferromagnetic component couples ferromagnetically with those of adjacent planes for x<0.2 and antiferromagnetically for x>0.2. The La0.8Y0.2Mn2Si2 compound displays a F-AF transition as a function of the temperature. The in-plane antiferromagnetic Mn moment components are smaller than those measured in the corresponding germanides. These results are discussed and compared with previous results of the La1-xYxMn2Ge2 compounds. The Mn magnetic behaviour is consistent with bibliographic data on NMR experiments and Mossbauer spectroscopy. (C) 1998 Elsevier Science S.A.