Abstract

The synthesis, crystallochemical and magnetic properties of sulfide spinels based on manganese and lutetium are reported. The stoichiometric non-substituted compound MnLu 2S 4 is a normal spinel, with manganese at the tetrahedral sites and lutetium at the octahedral sites. The experimental magnetic moment indicates a 2+ oxidation state for Mn. Partial substitution of lutetium by Er and Ho slightly weakens the antiferromagnetic character of the Weiss parameter (? = -15 K for MnLu 2S 4) due to a larger separation of the Mn 2+ ions, but it does not create any magnetic interaction, neither between the RE ions nor between the manganese spins. Inversely, 10% substitution of lutetium by chromium Cr 3+ (MnLu 1.8Cr 0.2S 4) triggers long-range ferromagnetic interactions below T c = 67 K, although antiferromagnetic components still predominate. The ordered state, ferrimagnetic or AF-canted type, is studied by ZFC/FC cycles under different fields and temperatures. © The Royal Society of Chemistry 2006.