Neutron diffraction study of magnetic ordering in PrCu2Si2, PrCu2Ge2, PrFe2Ge2 and NdFe2Ge2

A neutron diffraction study of polycrystalline PrCu₂Si₂ [1], PrCu₂Ge₂ [2], PrFe₂Ge₂ [3] and NdFe₂Ge₂ [4] intermetallics carried out at liquid helium temperature shows the presence of a collinear antiferromagnetic order below T_N = 19 ± 1 K [1], T_N = 16 ± 1 K [2], T_N = 9 ± 1 K [3] and 13 ± 1 K [4]. Magnetic moment, parallel to the c-axis is localized on RE ions only. The magnetic structure of these compounds consists of ferromagnetic layers perpendicular to the c-axis coupled antiferromagnetically with sequence +-+- for PrCu₂Si₂ and PrCu₂Ge₂ and +--+ for PrFe₂Ge₂ and NdFe₂Ge₂. The RE moments amount close to the free ion values for Fe containing compounds but are smaller in those containing Cu suggesting a fairly strong influence of crystal field.