The effects of magnetic dilution on the magnetism in the two-dimensional (2D) oxide systems Sr1 +xLa1 –x Fe1 –xSnxO4 and SrLaFe1 –xGaxO4 have been studied by Mossbauer spectroscopy and magnetometry. The end-member, SrLaFeO4, has a Neel temperature (TN) of 330 K, and shows some degree of magnetic relaxation for T/TN > 0.9. Diamagnetic substitution results in increased relaxation at concentrations where magnetic percolation is still effective. The magnetic susceptibility shows pronounced hysteresis effects. The possible role of the inter-planar interactions in determining the magnetic behaviour of these materials is discussed.
