Magnetic ordering of the R4Sb3 compounds (R = Pr, Nd, Sm) and of Pr2Nd2Sb3

Magnetization and neutron diffraction studies have been performed on Pr4Sb3, Nd4Sb3, Sm4Sb3 and on the Nd2Pr2Sb3 solid solution (all cubic anti-Th3P4-type, Space group I4¯3d, N. 220). Magnetization data on Sm4Sb3 reveal a ferromagnetic transition at TC = 168 K. The neutron diffraction study indicates a spin-canted commensurate antiferromagnetic structure below TC = 37 K and 52 K for Pr4Sb3 and Pr2Nd2Sb3 compounds, respectively; for Nd4Sb3, on lowering the temperature first a ferromagnetic structure appears at TC = 77 K which is followed below TC2 = 39 K again by a spin-canted structure. At 2 K the magnetic moments amount to ∼2.89 μB/Pr3+, ∼2.86 μB/(Pr0.5Nd0.5)3+ and ∼2.98 μB/Nd3+, respectively for Pr4Sb3, Pr2Nd2Sb3 and Nd4Sb3. The magnetic propagation vector is in all cases κ = [0, 0, 0]. The canting increases when going from Nd4Sb3 over Nd2Pr2Sb3 to Pr4Sb3.