Magnetic properties of R3Cu4Sn4 (R=La, Pr, Nd and Sm)

Abstract R 3 Cu 4 Sn 4 (R=rare earth) compounds crystallise in the orthorhombic, Gd 3 Cu 4 Ge 4 -type structure with space group Immm. There are two symmetry-inequivalent crystallographic sites for the rare earth ions in this structure. We have studied the magnetic properties of compounds with R=La, Pr, Nd and Sm. Both the symmetry-inequivalent Sm ions are found to be in the trivalent state. While La 3 Cu 4 Sn 4 is diamagnetic at room temperature, the other members of the series have antiferromagnetic ground state. Multiple magnetic transitions are observed in Sm 3 Cu 4 Sn 4 , similar to the behaviour in Ce 3 Cu 4 Sn 4 and Gd 3 Cu 4 Sn 4 studied earlier. The Neel temperatures do not follow the trend expected on the basis of de Gennes scaling. The heat capacity data indicate that crystal electric field splitting in these compounds is relatively low.